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Book Excerpt: Reef Aquarium Fishes

Organized by family for easy reference, each profile in Reef Aquarium Fishes includes all essential care, feeding and husbandry advice. The species profiled include all available reef aquarium choices, with scores of seldom seen, rare and recently discovered species. Written by the worlds most-read, most respected expert on marine fishes for the home aquarium, The PocketExpert Guide to Reef Aquarium Fishes is a must-read for any fish enthusiasts.

About the Author

Scott W. Michael is an internationally recognized writer, underwater photographer, and marine biology researcher specializing in reef fishes. He is the author of the Pocket Expert Guide to Marine Fishes (Microcosm/TFH), the Reef Fishes  series (Microcosm/TFH), and Reef Sharks and Rays of the World (Microcosm/TFH).

Having studied biology and the University of Nebraska, he has been involved in research projects on sharks, rays, frogfishes, and the behavior of reef fishes. He has also served as a scientific consultant for National Geographic Explorer and the Discovery Channel. His work has led him from Cocos Island in the Eastern Pacific to various points in the Indo-Pacific as well as the Red Sea, the Gulf of Mexico, and many Caribbean reefs.

A marine aquarist since boyhood, he has kept tropical fishes for more than 30 years, with many years of involvement in the aquarium world, including a period of retail store ownership. He is a partner in an extensive educational website on the coral reef environment,

Scott lives with his wife, underwater photographer Janine Cairns-Michael, and their Golden Retriever, Ruby, in Lincoln, Nebraska.

Excerpt from Hogfishes (Genus Bodianus)

The hogfishes are some of the hardiest members of the wrasse family. As a whole, they are durable aquarium fish that readily accept most aquarium fare, while ignoring all live corals. Most can be kept in reef aquariums as juveniles, but as they grow they will eat worms, snails, small clams, and crustaceans. The size of the aquarium needed to harbor a hogfish will depend on the species—most small to medium-sized members of the family (i.e., those species that attain a maximum length of less than 10 in. [25 cm]) can be kept in tanks ranging from 20 to 75 gallons (76 to 285 L), while more robust species require a tank of 135 gallons (513 L) or larger once they reach adult size. They need hiding places as well as ample swimming room.

Hogfishes, unlike certain other wrasses, do not bury in the substrate, so the depth of sand in your tank is of little concern. However, several of these fishes will hunt buried prey items by blowing jets of water at the finer substrate. This predatory behavior is fascinating to watch and will also stir the upper layers of the substrate.

Spanish Hogfish (Bodianus rufus): a graphic warning about hogfish feeding habits—motile invertebrates, such as brittle stars, are likely to meet this fate. Photograph by Scott W. Michael.

Many hogfishes will not tolerate the presence of members of their own species in the same tank, but they can be kept with other members of their genus. One caution: avoid placing two similarly colored species in the same tank.
As far as unrelated species are concerned, hogfishes can be belligerent toward smaller fishes, more docile species, or those fishes introduced after the hogfish has become an established resident of the tank. The moderate- to large-sized hogfishes should be kept with fish species that can hold their own, like lionfishes, squirrelfishes, soldierfishes, smaller groupers, goatfishes, angelfishes, hawkfishes, medium-sized damselfishes, sand perches, and less aggressive triggerfishes. Adding a hogfish to an established community of aggressive fishes, however, can cause the hogfish to remain hidden most of the time and never acclimate. Of course, large frogfishes, scorpionfishes, and groupers will eat any hogfish that they can swallow whole. While the larger hogfish species simply won’t fit into the average reef tank community, some of the smaller members of this group are worthy of consideration. Choose carefully, based on size and feeding habits.

Bodianus mesothorax. Photograph by Scott W. Michael.

Bodianus mesothorax
Mesothorax Hogfish
Maximum Length: 7.5 in. (19 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus mesothorax juvenile. Photograph by Scott W. Michael.

Bodianus diana. Photograph by Scott W. Michael.

Bodianus diana
Diana’s Hogfish
Maximum Length: 9.8 in. (25 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus perditio. Photograph by Scott W. Michael.

Bodianus perditio
Goldspot Hogfish
Maximum Length: 31.5 in. (80 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Threat to other invertebrates.

Bodianus izuensis. Photograph by Scott W. Michael.

Bodianus izuensis
Izu Hogfish
Maximum Length: 4.3 in. (11 cm).
Aquarium Suitability: This species is generally durable and hardy, with most individuals acclimating to the home aquarium.
Reef Compatibility: Safe with stony corals. Safe with soft corals. Threat to ornamental crustaceans. Occasional threat to some other invertebrates.

Excerpted from the PocketExpert Guide to Reef Aquarium Fishes by Scott W. Michael. ©Microcosm/ TFH Publications. Used by permission.

Posted October 16th, 2014.

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Book Excerpt: Clownfishes and Other Damselfishes

Clownfishes and damselfishes are among the most popular aquarium species, particularly for beginning aquarists. Written by a recognized authority on marine ornamental fishes, this comprehensive guide covers topics essential to keepers of these beautiful aquatic pets including selection, feeding, water requirements, diseases, breeding, and more. Full-color photos show over 20 species of clownfish and damselfish, while sidebars, charts, and tip boxes illustrate key points to consider.

About the Author

Jeff Kurtz is a freelance writer and editor who lives in Toledo, Ohio with his wife, Melissa, and two children, Aidan and Hannah. In addition to editing the health-and-fitness publication Healthy Living News, he is the Senior Consulting Editor for Tropical Fish Hobbyist Magazine and has authored or coauthored several additional books for TFH Publications, including The Simple Guide to Marine Aquariums, The Simple Guide to Mini-Reef Aquariums, The Super Simple Guide to Landscaping Your Garden Pond, and the Saltwater Aquarium Problem Solver. An avid aquarium hobbyist for almost three decades, Jeff focuses primarily on marine fish and invertebrates but enjoys freshwater fishkeeping, as well.

Excerpt from Chapter 4: Diet and Feeding for Clownfish and Damselfish

The majority of pomacentrids that you’re likely to encounter are omnivorous. In nature, some, such as the gregories (Stegastes spp.), have a diet that includes a greater proportion of algae, while others, such as the various Chromis species, rely more heavily on zooplankton. But few pomacentrids are so specialized in their diet that they completely exclude meat or veggies. That’s great news for hobbyists because, as you might expect, fishes that have a generalized diet typically adapt better to aquarium fare and have a much better survival rate in captivity compared to specialized feeders.

The pomacentrids in general are enthusiastic, opportunistic feeders. Offer yours a wide variety of foods. Photograph by Ligo/Shutterstock.

Variety Is the Spice of Life

So, being omnivores, pomacentrids should be offered a diet that is not exclusively plant- based or exclusively protein-based. This is very easy to do nowadays, as the selection of fresh, frozen, dry, and freeze-dried aquarium foods available to hobbyists has never been better.

Your pomacentrid menu should include items such as a staple pellet or flake, spirulina pellets or flakes, frozen mysid shrimp, frozen formulas for both omnivores and herbivores, and, at least occasionally, fresh meaty foods of marine origin, such as clams, shrimp, scallops, and fish, chopped to fit the mouths of pomacentrids.

Crazy Over Clams

Though it’s the rare pomacentrid that won’t start feeding shortly after purchase, it can sometimes take a day or two to get some specimens interested in eating. This is nothing compared to some marine fishes, such as certain butterflyfishes, which may take several days or even a week or more of coaxing with foods of all sorts before they’ll deign to accept anything you offer, but, nonetheless, it can be disconcerting when a clownfish or damselfish ignores your offerings. In such cases you can almost always win over a picky pomacentrid with chopped fresh clams. In fact, there’s just something about the scent of fresh clam in the water that really rings the dinner bell for almost any marine fish.

Shucking the fresh clams and chopping the meat is a bit labor-intensive, but you’ll find that it’s well worth the effort. Make sure the clams you purchase are still alive. Choose only those with their shells clamped tightly shut. Skip any that have gaping shells or an off odor, as they are either dead or dying. I usually buy a large quantity of clams, shuck and chop them all at once, set some of the fresh meat aside in the refrigerator to feed over the course of a few days, and freeze the rest for future use.

I prefer to freeze chopped clams in serving-size batches, so I usually dole out equal-sized portions of the meat into an ice-cube tray. That way, whenever I want to offer my fish a nutritious treat I simply pop one of the servings out of the tray, thaw it, drop the bits into the tank, and watch the fish go crazy!

Cyclops for Small Mouths

A great food to use when trying to elicit an initial feeding response from smaller pomacentrids, especially those that feed on tiny zooplankton in nature, is frozen cyclops. Cyclops is a popular item for feeding sessile invertebrates in reef systems, but I’ve found that most pomacentrids can’t resist them either.

When feeding very small foods such as cyclops, it’s helpful to temporarily shut down your filtration and water pumps so there is no water movement. It doesn’t take much force to suck these tiny crustaceans into a sump overflow or filter intake or to scatter them all around the aquarium so the fishes never even notice them. But if they are concentrated in one area and allowed to sink slowly to the bottom, they’ll get the attention of your fishes and it won’t take long for them to start snicking up these minuscule morsels. A little goes a long way when you’re using cyclops, so be careful not to overdo it!

Incidental Veggies

If your clownfish or damsel happens to share an aquarium with a herbivorous fish, such as a tang or rabbitfish, there’s an easy way to make sure your pomacentrid gets its greens. That is, provide the tang or rabbitfish with a sheet of dried marine algae, such as sushi nori or red or brown marine algae, to nibble on each day. Pomacentrids generally won’t tear algae off the sheet, but they will gladly snap up the tiny bits that float around in the water column after the tang or rabbitfish rips into the sheet.

Tasty Tidbits Crawling in the Tank

Though it’s not necessary to feed live foods to pomacentrids, they will certainly appreciate and benefit from eating them, and there are various ways—short of actively culturing them or buying them in small, cost-ineffective batches from your local dealer—to provide an ongoing supply of nutritious live foods that your clownfish or damselfish can nibble on.

Aquascaping your tank with copious quantities of quality live rock is one way to introduce populations of these edible organisms. As your system matures, all sorts of little critters will hatch out from the rocks, such as pods—amphipods and copepods—various worms, mollusks, and echinoderms, and clownfishes and damselfishes will gladly gobble up many of them.

Installing a live-sand substrate—or seeding a non-live sand bed with a small quantity of live sand to get the populations started—also is a good way to enhance the microfauna in your system.

Live rock provides clowns and damsels with myriad small organisms upon which to browse. Photograph by Iggy Tavares.

But perhaps the best way to provide a steady supply of live foods for hungry pomacentrids is to connect some form of refugium to your aquarium. A refugium is essentially a vessel that is separate from your main aquarium but shares the same system water (water is drawn from the display tank, flows through the refugium, and is then pumped back into the display tank). A sump or aquarium of any size can be converted for this purpose. You can also choose from the various commercially manufactured hang-on-tank refugia that are available on the market.

As the name suggests, a refugium provides a safe haven, or refuge, for organisms that would be either eaten or harassed in your display tank. These organisms could include the aforementioned amphipods, copepods, and other desired microfauna, as well as fishes or invertebrates that have been injured or are the target of territorial aggression. Because they are isolated from predators and tormentors, organisms kept in the refugium have the opportunity to reproduce more abundantly than they could in the display tank or to recover from tankmate-inflicted injury.

By placing some pieces of quality live rock and/or a bed of live sand in the refugium, you can establish healthy populations of edible microfauna. As these populations grow, some of these little organisms, along with their eggs and larvae, will be carried into the display tank, where the fish can gobble them up. Those that avoid being eaten will help to establish populations in the main tank, thereby increasing the overall biodiversity of the system.

I should add that many hobbyists also grow various forms of macroalgae, such as Chaetomorpha spp. (a.k.a. “chaeto”) and Gracilaria spp., in their refugia for the purpose of nutrient export. These algae take up dissolved nutrients, such as nitrate and phosphate, from the water, and the aquarist routinely harvests a portion of the algae, thereby removing the nutrients from the system. So, in addition to providing an ongoing smorgasbord of pods, worms, and other tiny critters, a refugium can help to keep your aquarium’s water quality at its best.

Should You Feed Live Foods?

Of course, live foods, such as mysid shrimp and newly hatched and adult brine shrimp (preferably enriched by feeding with a vitamin supplement), will be accepted with gusto by clownfishes and damselfishes and can certainly be offered as an occasional treat. However, with the variety of high-quality prepared fish foods on the market today, it’s really not necessary to offer live foods to pomacentrids on a routine basis. An exception must be made if you decide to breed clownfishes, as the larvae must be fed live marine rotifers and newly hatched brine shrimp, but we’ll get into that in greater detail in Chapter 8.

Whatever you do, try to avoid getting too lackadaisical in your feeding, for instance by relying too heavily on only one dry or frozen food for your own convenience.

Kicking Up the Nutritional Value of Your Pomacentrid’s Repast

Offering a varied diet is the best way to ensure that your clownfish or damselfish isn’t missing an important element in its diet, but as added insurance against dietary deficiencies it’s a good idea to occasionally enrich your pomacentrid’s food with a nutritional supplement.

Soaking dry or frozen foods with one of the liquid supplements that are available on the market (most contain important vitamins and highly unsaturated fatty acids, or HUFAs) prior to feeding them to your fishes will help to enhance the nutritional value of the foods, which, in turn, will keep your fishes healthier, more colorful, and better able to recuperate from injury or illness. These products can also be fed to live foods—such as brine shrimp—in order to enhance their nutritional value by adding them directly to the water in the culture container.

Excerpted from the Aquarium Success Guide to Clownfishes and Other Damselfishes: The Complete Guide to the Successful Care and Breeding of these Hardy and Popular Marine Fish by Jeff Kurtz © TFH Publications. Used by permission.

Posted July 6th, 2012.

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Book Excerpt: Tetras and Barbs

Tetras and barbs are a mainstay of the tropical fish hobby. Most people keep a community tank, and most community tanks rely heavily on tetras and barbs for color and action. Until now, however, there has not been a definitive book that covers these popular species exclusively. This book answers that need. Written by a recognized leader in the field of keeping and breeding tetras and barbs, the text provides a good overview of the care for these aquatic gems.

 About the Author

Since entering the hobby in 1989, Randy Carey has been keeping and breeding all types of small, soft-water fishes, but he specializes in the scatterers (tetras, barbs, danionins, rasboras, etc.). His aquaria room is lined with seventy-plus aquaria that span the roles of display, breeding, and various auxiliary uses. As an active member in the Minnesota Aquarium Society he is the first to attain the club’s Lifetime Award, earned by his breeding accomplishments.

Randy established one of the first aquarium web sites (Randy’s Fishroom in 1996) and probably the first aquarium blog (1997-2004). Since 1999 he has contributed a column, several feature articles, and photos for the pages of Tropical Fish Hobbyist Magazine. When traveling across the United States and Canada for speaking engagements, he delivers advanced topics to aquarium societies and tailors common-interest presentations when addressing non-aquarists. Randy maintains this book’s support site at

Excerpt from Chapter 2: Tetras and Their Relatives


Spanning so many species and lineages, the tetras also span many shapes and sizes: from the disk-shaped silver dollars to the extremely elongated Iguanodectes, and from the miniature amber tetra (Hyphessobrycon amandae) to the large pacu and piranha. No one color pattern or set of markings visually defines the tetras. Yet they do share some finnage features.

The caudal fin is forked into an upper and lower lobe. The fishes possess a single dorsal, which is short (front-to-back, where the fin runs along the body). An adipose fin is almost always present. But these features are common, not distinguishing, throughout all characins and (aside from the adipose) also most cyprinids.

The finnage that best distinguishes the tetras is the long anal fin. Typically it begins under or just behind the dorsal fin and runs almost up to the caudal. Classic examples are worn by the black tetra (Gymnocorymbus ternetzi), bleeding hearts, all Hyphessobrycon, silver dollars (Metynnis), and so many others. While this long fin is a signature feature centered in the tetras, it is represented in a few families closely related to Characidae: strongly present in the closely related hatchetfishes, and less long but still observable in the African tetras (Alestidae) as well as in Cynodontidae and Acestrorhynchidae.

Aquarium Strategies

Most tetras are quite similar regarding their aquarium care. However, three of the tetra subfamilies (Characinae, Serrasalminae, Bryconinae) vary enough that we must adjust our strategies accordingly.

Core Tetras

These are the fishes that have stereotyped tetras as relatively small and peaceful. They provide the lively movement in the middle strata of the aquarium. With nature offering literally hundreds of species, one can find a wide variety of colors on varying body shapes. Some of the most intense colors are found in this group: cardinal tetra (Paracheirodon axelrodi), serpae tetra (Hyphessobrycon eques), lemon tetra (Hyphessobrycon pulchripinnis), and blue king tetra (Inpaichthys kerri). These tetras also provide some of the best schooling fishes (such as neons and rummy-noses) as well as dramatic group/pack behavior (the various rosy tetra species). Tetras are not loners, so each species that is displayed should be represented by several specimens—never singly or even as just a pair.

The core tetras include some of the most brightly colored species, such as the lemon tetra (Hyphessobrycon pulchripinnis). Photograph by MP. & C. Piednoir.

If your goal is for a simple display with just a single species, select tetra species that contribute some dramatic feature: color, finnage, tight schooling, or intense pack behavior. I’ve seen an aquarium show entry stocked only with a school of the intensely blue Inpaichthys kerri that was so impressive that it won the coveted “aquarium beautiful” award.

If you are planning a community of several species, plan the species selection to provide visual contrast among the various tetra species by varying color, body shape, finnage, and behavior.

If the lower level- and bottom-dwelling fishes, such as catfishes or cichlids, are the showpiece specimens in your aquarium, you may want the mid and upper levels occupied by background fishes. This role can be filled by tetras with subtle coloring and that school loosely (instead of schooling in synchrony or interacting as a pack).

Provide significant aquascaping to relax the fish and to provide temporary refuge. Plants, in particular, will draw out the natural behavior and strong colors that are otherwise muted in captivity. Likewise, most tetras show their best color in water that is soft (6 dH or less) and slightly acidic (pH 5.5–6.8). Many of the tetra species come from blackwater streams, and these welcome more extreme conditions: 1–2 dH, pH 4.5–6.0.

As a general rule, the core tetras do not eat plants. Flakes should complement any tetra diet, but they do prefer meaty foods, be they frozen or live. Tetras eagerly attack small live foods like fruit flies, mosquito larvae, blackworms, and brine shrimp.

Characinae: Scale Eaters

The dentition and gut contents identify many of the Characinae as scale eaters. Yet aquarists have successfully kept other aquarium fishes with several of these species. Perhaps success is attributed partially to keeping them well fed—nature studies reveal that scale eating increases as food supplies decrease. If you give them tankmates, keep them well fed and make sure the other fishes are not smaller. Keep a watchful eye on the tank’s social dynamics and take action as needed.

Bucktooth tetra (Exodon paradoxus). Photograph from TFH Archives.

Serrasalminae: Pacus, Silver Dollars, Piranhas

The fishes of this tetra subfamily are larger and have extreme feeding habits compared to the core tetras. The large pacus—two to four feet (60 to 120 cm) long or more—are vegetarians and outgrow a 55-gallon (200-liter) tank within their first year. If you must keep these fishes, prepare for a multi-hundred-gallon aquarium designed without plants. In contrast, the silver dollars are 4 to 6 inches (10 to 15 cm) long. Their sizable disk-shaped bodies adorned with bright, silvery scales is eye-catching, making them popular and showy fishes. Their diet is mostly vegetarian, so plants seldom survive within their aquascape. Finally, the over three dozen species of the infamous piranha are sizable (typically six to ten inches, 15 to 25 cm), most should be kept in a group, and they require very large tanks. Typically they are kept in a species tank to display their attitude and feeding behavior. Aquarists have had mixed results when keeping them with other fishes, and failures seem to involve underfeeding.

Myleus rubripinnis. Photograph from TFH Archives.

Bryconinae: Brycons

These sizeable trout-like fishes are more important as food than as aquarium inhabitants. Most are unremarkably silver and large (6 inches to over 2 feet, 15 to 60 cm). Resigned to a background presence if used in aquaria, they arguably serve best as dithers or targets for larger fishes.

Triportheus albus. Photograph by Aaron Norman.

Excerpted from the Aquarium Success Guide to Tetras and Barbs: A Complete Guide to the Successful Care and Breeding of the Two Most Popular Groups of Aquarium Fish by Randy Carey © T.F.H. Publications. Used by permission.

Posted January 10th, 2012.

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Book Excerpt: The Simple Guide to Freshwater Aquariums

The Simple Guide to® Freshwater Aquariums (Second Edition) is the key to becoming a dedicated aquarium hobbyist is to succeed with your first aquarium. The Simple Guide to® Freshwater Aquariums concentrates on providing you with a complete plan and all the information you need to choose and use the right-for-you aquarium equipment and the right-for-you fish and plants: it wants you to succeed. The information is presented in a completely straightforward text that’s easy to read, easy to understand – and very definitely easy to put to good use.

About the Author:

David E. Boruchowitz is in his sixth decade of fishkeeping. He wrote and edited for T.F.H. Publications for more than a decade and has authored a large number of books on a variety of topics. He also served as Editor-in-Chief of Tropical Fish Hobbyist Magazine.

Excerpt from Chapter 5: What Options Do I Have?

Hang-On Outside Filters

The hang-on outside filter is the most popular and versatile design, and it’s the one I recommend for your first aquarium. This filter has undergone a lot of improvement since the early air-driven models, which were nothing more than a box filter hanging on the back of the tank. They were fed with siphon tubes, and an airlift returned water to the tank through the filter medium. Modern power filters use a water pump to draw water up from the tank and into the filter, where it flows through chambers of filter media and returns by gravity overflow to the tank.

Although there are models available that contain chambers into which you can heap the filter media of your choice, most filters today have modular filter components that you can mix and match and slide into the filter sections. That makes it much easier to service the filter, and it also ensures that water will not find its way around the media instead of going through them, since the medium cartridges fit snugly into the compartments.

Usually a particular filter is available in a series of sizes, each successive one being both larger (and thus having more room for media) and more powerful (in having a stronger pump that delivers more gallons per hour). The idea here is that you can buy a filter sized to your particular aquarium. My suggestion is that you ignore such advice and choose one of the largest models. What?

First of all, you get more filtration for your dollar with the larger ones. Second, if you later upgrade to a larger tank, the larger model may still be adequate. Third, there is basically no such thing as too much filtration. An absolute minimum would be a unit that delivers a flow rate of five or six times the tank volume per hour, but ten times is even better. This is mainly because of biofiltration—more flow means more bacterial contact with more oxygenated water. It also improves the aeration of the water, making sure oxygen levels stay at optimum levels for the fish throughout the tank.

Last but not least, the ratings on most filters are nearly useless. Typically you might see something like “for aquariums of 10 to 60 gallons.” A filter truly adequate for a 60-gallon (230-liter) tank would have a flow rate that would overpower a 10-gallon (40-liter) tank. Although I said that it’s not possible to over-filter a tank, you also do not want the flow rate to be so powerful that it creates a whirlpool effect, with the fish being whipped around the tank all the time. The real problem, however, is that it is unlikely that the filter actually has an effective flow rate of 300 gallons per hour (gph), making it unsuitable for a 60-gallon tank. But even the gph rating can be misleading. The filter’s pump may be rated at, say, 150 gph, but that doesn’t mean that 150 gallons go through the filter every hour. Just pumping the water through the empty system will cut down on the flow; even the introduction of new media will reduce the flow, and as the filter gets dirty the flow decreases even more.

So what do you do? The solution is to buy the biggest and most powerful power filter you can. If you can hang it on the tank, it’s probably not too big. I have very successfully used a spare 400-gph filter on a 20-gallon tank; when I no longer needed it there, the filter went back on a 55-gallon tank. The filter was slightly narrower than the back of the tank on which it hung, but it worked very well. An even better idea is to get two power filters, each big enough to handle the tank alone. Not only does this give you greatly improved filtration and aeration, but it also provides a backup if one filter suddenly breaks down, and it permits you to clean them on an alternating schedule, minimizing the loss of biofiltration capacity. Remember, there’s no such thing as overfiltration, only underfiltration.

Canister Filters

Canister filters have some superior characteristics, but they are the most expensive way to go. One of their preferred characteristics is that they can be placed away from the aquarium (usually under it) and are connected to the tank by hoses. This means that the tank can be placed almost flush against the wall, since there only needs to be enough room for a couple of pieces of tubing behind it.

The major filtration advantage canister filters provide is that the water flows through them under pressure. This is because the filter is a closed system. Water is drawn from the tank and then flows into the filter, through the media, and back to the tank. It is driven by a water pump that, depending on the particular design, is either integral with the filter canister or plumbed into the system. This means that considerable power can be generated, which in turn means that the water is forced through the media under pressure, providing maximum filtration benefits. This also permits in some models the use of diatomaceous earth (a powder made up of diatom skeletons) as a filter medium; water will not really flow through it, but it can be forced through it under pressure. Diatomaceous earth filtration is meant as a temporary filter to “polish” the water—the diatomaceous earth cartridge is replaced by a regular mechanical medium for full-time use.

Canister filters work well and are excellent for large aquariums. They don’t do much that a couple of high-power outside power filters can’t do, but they are very efficient filters, and many aquarists prefer them, despite their complexity.

Most of that complexity is simply plumbing, since you have to get water from the tank to the canister and back again. There are many options in how you set up a canister filter, which is why some of them do not include fittings, which have to be purchased separately. Fortunately, the major brands currently on the market all include fittings and tubing. Many canister filters have several options for the return, from simple tubing outlets to spray bars that diffuse the return flow over the entire surface of the tank.

Whatever filter you choose, if it does not have a true wet-dry option, you should use a sponge filter, add-on rotating contactor, or other biofilter in addition to it.


Recently “wet-dry” filters have enjoyed greater popularity for use with freshwater aquariums, although they have always been used mainly for marine aquariums.

Just what is wet-dry, anyway? Well, obviously, if filters are filtering aquarium water, they cannot be dry, but the name makes sense because these filters make use of a medium that is kept moist but not fully submerged in water. This is the “dry” part of the filtration process.

The purpose of this type of medium is to increase biofiltration, which it does significantly, because air has much more oxygen in it than the most highly oxygenated water does. With the vastly improved oxygen supply, many times the number of bacteria will grow in a given area, and they will process wastes at a much greater rate.

The design of wet-dry filters is quite varied, but they share the feature that somehow water is dripped, splashed, sprinkled, trickled, or sprayed onto a high-surface-area medium, through which it percolates before returning to the tank. Some power filters incorporate a wet-dry section as the final stage, but there are also some that claim to do so and don’t.

Excerpted from The Simple Guide to® Freshwater Aquariums (Second Edition) by David E. Boruchowitz. © T.F.H. Publications. Used by permission.

Posted December 16th, 2011.


Book Excerpt: Lionfishes and Other Scorpionfishes


Aquarium Success: Lionfishes and Other Scorpionfishes The venomous but beautiful scorpionfishes are extremely popular among home aquarists, with many species readily available in pet and aquarium stores. Written by one of the leading experts on this group of fish, this exclusive guide is the only trade book on the subject and covers topics essential to ensure a healthy and thriving tank, highlighting the top 25 species with profiles of their natural range, size, behavior, aquarium suitability, and specific care requirements.

About the Author:

Frank C. Marini III, PhD, born and raised in Hudson, Massachussets, is a long time fish nerd. Working as a stem cell biologist by day, Frank’s passion for keeping scorpionfish and their kin has lasted more than 30 years. His scientist side affords him a unique perspective into animal behavior, and his fish nerd side keeps him curious and motivated to find the keys to unlocking successful long-term husbandry of these remarkable fish. In 1995, Frank was credited with the first successful breeding of Banggai cardinalfish in captivity, and his writings have inspired thousands of fishkeepers to delve into marine fish breeding. For the past 15 years he has bred many species of marine fish, and accompanying this, he has moderated web forums on fish breeding and keeping aggressive and predatory fish in the home aquarium. Frank can be contacted at

Excerpt from Chapter 1: Scorpion Biology

Distribution and Habitat

Lionfishes and scorpionfishes are widespread in the world’s oceans but are primarily found around coral reefs. Man has aided lionfish distribution over the past 50 years, with Pterois miles entering the Mediterranean Sea from the Red Sea via the Suez Canal. Also, P. volitans and P. miles were introduced into the Atlantic Ocean along the U.S. East Coast and have become established there. Scorpions are found in water depths ranging from 2 to 1260 feet (less than a meter to 380 meters), on hard and soft bottoms, coral reefs and artificial substrates (e.g., sunken ships or oil rigs). In corals reefs and rocky outcrops, the fish hide in caves and crevices and underneath rock overhangs. Many small scorpionfishes live among the coral rubble, while some larger forms lie in exposed areas waiting for passing food. Many species are well camouflaged, as they are replete with dermal appendages, muted color tones, and skin flaps and tassels that allow them to disappear from plain sight. A sedentary lifestyle enhances their ability to blend in and ambush unsuspecting passers-by.

Biological Features

Scorpaeniforms have many adaptations in anatomy and behavior that serve them well in the wild, adaptations that must be taken into account when keeping these animals in captivity.

Ecological Role

Easily outpaced by other animals, scorpionfish and lionfish are slow-moving hunters. Lionfish tend to appear conspicuous, so they rely on their unusual colorations and fins to discourage potential predators. On the reef, lionfish are top predators, as they are active hunters who ambush their prey using outstretched fins to slowly herd and corner their prey. As for scorpionfish, their strategy is different. They are extremely stealthy and sedentary, often sporting camouflaging coloration, feeding on prey that comes too close.

Their hardiness, graceful movements, and stunning appearance have made lionfish extremely popular in the marine fish hobby—in spite of their venomous spines.


Lionfish are active predators of smaller fish, crabs, and shrimp. They move by slowly undulating the soft rays of the dorsal and anal fins, stalking and cornering prey with outstretched, expanded pectoral fins. Their kill shot is a lightning-quick snap of the jaws, swallowing their prey whole in an instant. In the wild and in captivity, these fish can be cannibalistic. Lionfish appear mostly nocturnal, given their tendency to retreat to hiding areas during the day. However, in captivity we clearly observe lionfish feeding throughout the day, indicating that in the wild recently fed individuals may merely be retreating to their hiding spot after eating.

Most scorpionfish remain motionless for hours, relying on concealment to aid in ambushing their prey and feeding whenever the opportunity arises. On the reef, they feed on a few organisms a day, although large scorpionfish may ingest only one larger prey every few days. Scorpionfish diets vary, with some large scorpionfish feeding exclusively on fish. Others of similar size demonstrate a wide dietary breadth, feeding on shrimp, crabs, and squid in addition to fish. Many small scorpionfish feed almost exclusively on small crustaceans and worms. Like lionfish, scorpionfish tend to hunt mainly at twilight—they’re crepuscular hunters—but they never pass up a meal opportunity, day or night.

Prey Capture

The cavernous mouths of many scorpaeniform fishes are disproportionately large compared to their body size, so they are able to take even very large prey. Prey capture takes place in three phases: 1) orientation to the prey item, 2) seizing the prey (expansion and compression of the mouth) and 3) manipulating and swallowing the prey. When a scorpionfish sees a prey item, eye movements indicate the scorpionfish is tracking the prey. The scorpionfish raises its head slightly, visually orienting toward the prey’s eyes. They attempt to orient their bodies toward the prey’s head. This adjustment precedes the fish’s rolling and pitching its pectoral fins to ensure the prey is within range.

Just before opening its mouth, the fish depresses its mouthparts, essentially spring-loading the mouth structures with potential energy to explode wide open for the strike. Bony fishes in general have similar mouth expansion biomechanics, but in scorpaeniforms mouth movement is so rapid that it creates a large lateral expansion, resulting in additional suction. The fish literally sucks the water surrounding the prey into its mouth, rendering the prey as powerless to resist as a surfer on a bad wave. Once the prey is in its mouth, the fish holds it securely with its curved conical teeth, frequently manipulating the prey with abbreviated mouth expansion and closure—in essence, readjusting the food item to ensure it is head first. Swallowing occurs with a raking motion of the throat teeth. This entire process occurs swiftly—complete prey capture has been recorded at 45 milliseconds for a stonefish, with mouth opening and closing occurring in under 20 milliseconds (Grobecker, 1983).

Scorpionfish are cryptic and sedentary relatives of the lionfish. This one is well camoflaged in a barrel sponge waiting for unsuspecting prey.

Defensive Behavior

Many scorpions rely on their cryptic coloration and sedentary nature to fend off predators. By being completely camouflaged, they rely on hiding in full view as a passive defense. Many have specialized body shapes and possess skin tassels that allow them to appear convincingly identical to algae tufts, rockpiles covered in sponges, or unpalatable crinoids. To supplement the camouflage, some scorpions mimic the undulating movement of local algae or debris; this is done, for example, by the leaf scorpions, whose bodies rock side-to-side, mimicking the wave action of local plants. However, if a predator stumbles across or threatens a scorpaeniform, the fish reacts. Initially it may flee, quickly settling into a new area, then quickly freezing again, remaining motionless. Alternatively, a few species possess brightly colored fin markings that are usually held in the closed, or darkened, position, such as on the bottom of the pectoral fin. These markings, called flashes or flasher fins, are rapidly exposed at a threat and may serve as a warning. Alternatively, the bright color flash may confuse or disorient predators.

Certain scorpaeniforms get their common names (stingfish, waspfish, etc.) from their ability to defend themselves with a venomous sting, although it’s used as a last-resort defensive weapon to prevent a repeated attack. Venom glands at the base of certain spines produce a venom that the fish injects via the spines. The venom immediately causes severe pain that just about guarantees a hasty retreat of the threat. Medical and scientific journals have documented numerous cases of human envenomation, and I’ve dedicated a whole section to this topic later in this chapter.

Multifocal Lensed Eyes

Lionfish eyesight consists of a multifocal optical lens in each eye, with a short focal length (Karpstam, 2007). Long focal lengths equate to high optical magnification of the image and low light-gathering ability, meaning they can see farther but require hunting during daylight hours, whereas short focal lengths correspond with higher light-capturing ability and less magnification of the target, meaning more evening time hunting of prey that swims nearby. Because lionfish possess eyes better suited for their crepuscular behaviors, they strike at food from short distances and do more low-light hunting.


Scorpaenids have many small teeth located on the upper and lower jaws in densely packed bilateral clusters, and in a small patch on the anterior roof of the mouth. These teeth appear functionally limited to grasping prey captured by the extraordinarily quick predatory strike. The pharyngeal (throat) teeth help them secure and swallow their meals.


Many scorpaeniforms lead an extremely sedentary lifestyle, and marine organisms (algae, hydroids, and bacteria that settle from the water column) can attach to them. Because of this, many have evolved a protective coating, called a cuticle. A cuticle is a thin white or opaque skin covering encasing the entire animal. The fish shed this cuticle to rid their bodies of these organisms. Some species, like Rhinopias, shed this cuticle weekly, and many others, such as lionfish, shed monthly or even less frequently. Shedding can take minutes to hours. Shedders shake their body rapidly until the cuticle tears off in small pieces. In home aquariums, cuticle shedding looks unsettling. In a lionfish, you’ll notice that the fish darts and dives, then convulses for a few seconds; a white, ghost-like tissue appears in the water. The cuticle protects the fish from illness, and excessive cuticle shedding indicates poor health, as they increase cuticle shedding during protozoan infection as a way of reducing their exposure.


Few published records of natural predators of scorpionfish and lionfish exist. One short report suggests that the piscivorous cornetfish Fistularia commersoni is a predator of Pterois miles. Judging by the presence and reverse orientation of a partially digested specimen of P. miles in the stomach of a large F. commersoni, the authors concluded that cornetfish may ambush lionfish from the rear, consuming them tail-first, allowing the venomous spines to fold harmlessly forward. In the home aquarium, venomous spines aren’t a deterrent to larger piscivores, as I’ve personally witnessed antennariids (frogfish and anglerfish) consume small lionfish. Additionally, other scorpions readily consume smaller ones. I have watched in horror as my large P. volitans engulfed two juvenile conspecifics. It is likely that natural lionfish predators include sharks, as many sharks consume noxious organisms without displaying ill effects from the poisons.

Social Structure

Lionfish are often seen moving about during the day, alone and in groups of two to six animals. They may live alone most of their lives, fiercely defending their home ranges from other lionfish. As juveniles, lionfish aggregate into small groups, and this cooperation probably increases their ability to gather food. During the spawning season, adult lionfish also may gather into groups, with males acting more aggressively than females. In many lionfish no clear sexual dimorphism or dichromatism exists—however, clear demarcation between sexes exists in Dendrochirus brachypterus, the dwarf fuzzy lionfish. Lionfish reproduce like many other fish, producing eggs that are fertilized outside the female’s body. There is little information about the social structure of most reef-dwelling scorpionfish species. Most observations about these fishes are from anecdotal reports from scuba divers and aquarists keeping them. We do know that most tropical species remain solitary, with occasional sightings of scorpionfish pairs, and the leaf scorpionfish have been noted in pairs and trios.

Excerpted from Lionfishes and Other Scorpionfishes: The Complete Guide to the Successful Care and Breeding of These Spectacular and Popular Marine Fish by Frank C. Marini, Ph.D. © T.F.H.  Publications. Used by permission.

Posted November 23rd, 2011.

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Book Excerpt: Catfishes

Lee Finely

Catfish enjoy a spotlight of their own in the aquarium hobby, famous for being a tank’s clean-up crew. There are hundreds of species regularly sold in pet stores and more varieites become available every day. The sheer number of catfish and their different requirements can seem daunting—interested fish keepers need a reliable source of guidance on these hard-working and often personable fish.

Aquarium Success: Catfishes gathers all the information an aquarist needs in one easy-to-read, completely illustrated book. Whether the huge amount of data on new catfishes has you feeling lost or you are just starting to get interested in them and want to learn more, this book is just what you need.

About the Author:

Lee Finley has been an aquarium hobbyist/professional for over 40 years. As an integral part of this, Lee has regularly written on various aquarial topics over the past 30 years and has over 335 published articles to his credit. Among these writings are included almost 12 years of a monthly book review column and almost nine years of a monthly catfish column in Tropical Fish Hobbyist Magazine.
Lee has enjoyed the pleasures of many different fishes over the years and many of his early experiences were predominately with cichlids. From there he moved on to catfishes and this fascinating group has kept him interested and challenged for the past 28 or so years. This interest has prompted some travel, and Lee has made four trips to South America (Brazil and Peru) to observe and catch catfishes in their natural habitat.
Lee has been involved in many other aspects of the aquarium hobby/industry. In the past he was owner/operator of an independent pet store. For the last 10 years, Lee has run a predominately mail order book business (Finley Aquatic Books) dealing in both new and used literature encompassing all aspects of the aquarium hobby and aquatic natural history.

Excerpt from Chapter 2: Foods and Feeding

On Feeding Catfishes

Once they’re settled into a given aquarium, most catfishes will not be shy when fed. But there are certain factors that you must keep in mind. These include, but are not necessarily limited to, the feeding styles of their tankmates (catfish and noncatfish) and the feeding styles, and levels of gregariousness, of the individual catfishes.

Try Several Small Meals

In general principle I don’t subscribe to any particular formula for how much food to offer at a particular feeding. This belief leaves out the various grazing catfishes who can be provided with vegetal foods (live algae, real vegetables) to eat constantly. For other catfishes, I prefer to feed a number of smaller meals throughout the day and evening. Your life schedule will have an effect on this, but ideally if you can feed two to four smaller meals a day it will be a much more natural way of eating for your catfishes. This even goes for the more predatory types that might be receiving some small live fishes.

Mix Things Up

When I feed I also like to mix up foods a bit instead of just using one food item. For example, if you’re using a flake food, which tends to sink slowly, you might also offer some commercial granules, pellets, or discs, which will sink faster. This will help to assure that catfishes feeding at the top, middle, and bottom of the tank will get their fair share of food.

I also like to use this technique when offering meaty foods. I will mix frozen brine shrimp and bloodworms and offer these together. This helps make a healthier meal. I also will mix in a bit of flakes too.

Targeted Feedings

If you have some shy catfishes who don’t respond well to feeding times during the day you might try some targeted feeding. Some of the catfishes that often tend to be slower or a bit shy (banjo cats come to mind) may not easily come out of their hiding places. If you have an idea where the shy catfishes are hiding you can deliver whatever foods you’re using directly to them with the use of a small food baster or one of the larger baby animal feeding droppers that are available.

While a great majority of catfishes are generally thought of as nocturnal, this isn’t the whole story. There are definitely some that are more light-shy than others and this needs to be considered when feeding. Consequently, it’s a good idea to do at least one feeding at night after the lights in the aquarium have been out for a while. In a more general community situation most of the fishes will respond to the dark by hiding away and/or sleeping. This will allow the catfishes, especially those that might be more shy, to come out and eat.

Observe Your Catfishes

There are no hard and set rules on how and when to feed your catfishes. Although they are a highly diverse group, many will easily fall into whatever feeding schedule you set up. But there are always going to be a few that may not readily fit into such a plan. Observe your catfishes closely and see what they like to eat and when they like to eat it. A little observation can go a long way in guaranteeing a healthy and well-fed catfish.

Excerpted from Catfishes: The Complete Guide to the Successful Care and Breeding of More Than 100 Catfish Species by Lee Finely © T.F.H.  Publications. Used by permission.

Posted October 19th, 2011.

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Nature Aquarium: Complete Works 1985-2009 By Takashi Amano

Nature Aquarium: Complete Works 1985-2009 By Takashi Amano

Nature Aquarium: Complete Works 1985-2009 takes you on a journey through over two decades of the most innovative and breathtaking designs from nature aquarium pioneer Takashi Amano.  In this collection of works from the world-renowned aquarist, over 200 vibrant, full-color photos display the captivating beauty of nature aquariums while providing detailed, step-by-step instructions on how to create your own aquatic masterpiece.  Along with expert advice on plant and fish selection, water chemistry, and maintenance, the author includes essays outlining aquarium aesthetics and his own personal design philosophies to inspire readers to create their own harmonious and tranquil nature aquarium designs.

Amano Image

The Real Pleasure of Keeping Discus in a Large Aquarium

Although the vividly colored hybrid discus is attractive, the wild original species also has a big appeal. Generally speaking, the wild strain is more timid than its artificially bred hybrid counterpart.  It tends to calm down better if an aquarium offers driftwood and aquatic plants where it can seek refuge. It becomes accustomed to a new environment and settles down more quickly if its environmental condition is kept as similar to the natural habitat as possible. For this reason, Nature Aquarium created in a large aquarium is more suitable for wild discus.   However, keeping discus in a layout has its own difficulties.  When a discus is introduced in an aquarium at first, it hides behind driftwood and does not come out to swim gracefully in an aquarium. Under such conditions, its body color darkens to blend into the shade. Although feeding can sometimes be effective for getting it acclimated to the aquarium environment as quickly as possible, it does not take well to artificially prepared food initially.  It may be necessary to devise some special measures to entice them, such as giving some bloodworms along with prepared food at the risk of fouling water, or putting other fish in the aquarium in the hope that discus will follow them to come out of hiding. After overcoming many difficulties and becoming accustomed to the aquarium environment, a discus not only graces the aquarium by regaining its beautiful colors, but it also starts to show its natural behaviors, such as spawning on driftwood. That will greatly add to the joy of keeping this fish. The real pleasure of keeping wild discus in Nature Aquarium is to bring out their natural beauty and behaviors by perfecting the habitat environment in an aquarium.

Excerpted from the book Nature Aquarium: Complete Works 1985-2009 by Takashi Amano (pgs. 56-57).  ISBN: 9780793806492. ©2011 TFH Publications, Inc.  Used with permission.

Posted December 14th, 2010.

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Book Excerpt: Lionfishes and Other Scorpionfishes

Lionfishes and Other Scorpionfishes (Aquarium Success)

Chapter 5

Species Guide: The Odd, Unusual, and Amazing

Genus Inimicus

These fish inhabit sandy and muddy bottoms in sea grass fields, estuaries, and neighboring reefs. Although Inimicus species prefer shallower water, there are records locating them in as deep as 90 meters (300 feet). There are about ten species, of which three are found with any regularity in the hobby. Inimicus differs from Choridactylus by its flattened snout, eyes set high on the head, and two free pectoral fin rays that are used as fingers. In Japan, Inimicus are cultured as a delicacy food, and induced ovulation using hormones to increase production has been reported (Takusima, 2003).

Like the other choridactylines, these stingfish spend their day half buried or mostly buried in the soft sand, with only their eyes, dorsal fins, and mouth exposed. Individuals frequently have their two free pectoral fin rays placed ahead of the body and dug into the substrate in case a food item zips by; the fish can then spring into pursuit. Some species have even higher-set eyes and an upturned mouth that allows the fish to bury themselves more completely to really surprise passing food. In the wild they eat mainly fish, but they readily take live shrimp.

Inimicus are some of my most favorite scorpions. I have kept fishes of this genus on and off for 10 years. Each of them had a distinct personality and very interesting hunting behaviors. Their strategies include an ambush attack from underneath the sand, a relatively fast stalking using the pectoral fingers to scamper quickly to the food, and a pounce from above. They readily fed on live ghost shrimp and small feeder guppies, and I successfully weaned them onto prepared foods, although it did take longer than I had hoped. These fish spend their day buried with just their eyes sticking out of the sand, and they spring to life when food hits the water. It is reported that Inimicus kept in groups will fight, but they never bother tankmates too large to swallow. Mine were hardy and disease resistant, ate consistently, and shed their cuticles with regularity. Another reminder: they pack a very potent sting, stronger than a lionfish sting.

Inimicus caladonicus

Common Names: Bearded ghoul, Caledonian sea goblin, Caledonian stinger, Chinese ghoul, demon stinger, demon stingerfish.

Size: 10 inches (25 cm)

Distribution: Eastern Indian Ocean: Andaman and Nicobar Islands; West Pacific: Australia, Papua New Guinea, and New Caledonia.

This fish is very similar to I. didactylus but differs in the coloration of its pectoral fins, in which the inner surface contains a dark band that runs through the middle and a dark band on the inner axial of the fin. Additionally, Caledonian sea goblins frequently have white spots in front of their elevated but wide-set eyes.

Sea goblin (I. caladonicus) photographed in the waters off Sulawesi, Indonesia. These fish dwell mostly in muddy- or sandy-bottomed water and seagrass beds.

Inimicus didactylus

Common Names: Bearded ghoul, demon stinger, devil stinger, longsnout stinger, longsnout stingerfish, popeyed sea goblin, spiny devilfish.

Size: 10 inches (25 cm)

Distribution: Indo-West Pacific: Thailand to Vanuatu, north to Ryukyu Islands and southeast China.

I. didactylus makes a fine aquarium resident. It requires at least 2 inches of fine sand or sandy substrate. In my experience this fish frequently comes in with amazing colorations—such as yellow, red, and white. The red variants look like living piles of red sponge with encrusting algae. Gray fish tend to have uniquely colored pectoral fins. I. didactylus differs from its congeners in the undersides of its pectoral fins: a sweeping yellow or white band with a darkened half-moon center. It also has a slightly upturned mouth.

Inimicus didactylus flaring out its brightly colored pectoral fins in a territorial display.

Inimicus filamentosus

Common Names: Barred ghoul, devil scorpionfish, filamented sea goblin, filament-finned stinger, two-stick stingfish.

Size: 10 inches (25 cm)

Distribution: Western Indian Ocean: the Red Sea and East Africa to the Maldives.

The filamented sea goblin appears to be an advanced form of Inimicus, as it has both an upturned mouth and high-set fused eyes, allowing it to almost completely bury itself and still efficiently ambush unsuspecting food. The species can be readily identified from other Inimicus by the presence of two extended filaments on the pectoral rays, and by the yellow, red flasher colors on the underside of its pectoral fins. I have not seen this fish in many other body colors except dull grayish brown, with pinkish overtones; however, has an image of a reddish pink specimen. This fish is quite uncommon at pet stores. Care and husbandry is the same as the other Inimicus species, if you can find it.

I. filamentosus showing the eye-catching pattern on its pectoral fins. This fish was photographed in the Red Sea near the Sinai Peninsula.


Once included in Scorpaenidae, subfamily Tetraroginae, the waspfishes are now considered a separate scorpaeniform family, Tetrarogidae. Features that exclude them from Scorpaenidae include a dorsal fin that originates above and in front of the eyes, in contrast to the scorpionfishes, in which the dorsal fin originates well behind the eyes. Waspfishes have contiguous-appearing dorsal, caudal, and anal fins, whereas scorpionfishes have those three fins separate. Waspfishes also possess small scales embedded into their skins, and they are more laterally compressed than typical scorpionfish (except the leaf scorpionfish). Taxonomic considerations aside, waspfish look like scorpionfish, act like scorpionfish, carry venom like scorpionfish, and require the same care as scorpionfish.

Of the many genera and species in this family, only three species (in two genera) are seen in the hobby with any regularity. These animals are wonderful aquarium specimens. Besides being relatively small, they are also extremely sedentary and spend most of their day in one spot or slowly hopping along the bottom in search of food. Always ensure that your waspfish’s tankmates do not out-compete them for food and do not pick on them as food items.

These fish blend well into dark substrates and piles of live rock. Aiding their external camouflage is their habit of slowly rocking side to side as if they are algae swaying in the current.

Waspfish are incredibly slow feeders and cannot be placed in a tank with any fast-swimming fish. I found them difficult to feed and only got them to eat live ghost shrimp; they had little interest in feeder guppies. Eventually I was able to wean them onto prepared frozen mysis shrimp; however, they always preferred live food.

The basic husbandry requirement for all the species of waspfish appears to be the same. They prefer a mellow community tank, with slow-feeding neighbors. Good tankmates would include: small scorpionfish, leaffish, and smaller antennarids (anglerfish). The tank can be aquascaped with small piles of live rock or rubble that include a few hiding spots, or even containing live macroalgae for the fish to hide in during the day. I’ve kept up to three waspfish in the same 30-gallon (115-liter) tank with no visible fighting, and as mentioned in the breeding section, I was able to get these fish to spawn.

Ablabys macracanthus

Common Names: Spiny leaf fish, spiny waspfish.

Size: 8 inches (20 cm)

Distribution: Indo-West Pacific.

This species is less commonly available than A. taenianotus but does show up occasionally. The dorsal fin crest starts ahead of the eyes, making it slant backward down to the face, while in A. taenianotus it is nearly vertical.

Ablabys taenianotus

Common Names: Cockatoo fish, cockatoo leaf-fish, cockatoo waspfish, leaf fish, rogue fish, roque fish, rouge fish.

Size: 6 inches (15 cm)

Distribution: Eastern Indian Ocean and Western Pacific

This is the more common species seen in pet stores. Individuals are varied in coloration, ranging from dark brown to golden, but usually are a solid color. Reportedly female cockatoo waspfish have single white spots or blotches above and below their lateral lines on both sides of their body, while males lack spots above the lateral line. Also male cockatoo waspfish are reported to have one or two white spots on the distal edge of their gill opercula, while females do not.

Although no longer considered to be in the same family as the scorpionfish, the waspfish are very similar in appearance, behavior, and care. A. taenianotus is shown here.

Paracentropogon longispinus

Common Names: Long-spined waspfish, whiteface roguefish, whiteface waspfish, wispy waspfish.

Size: 5 inches (13 cm)

Distribution: Indo-West Pacific: southern India to southern China and New Caledonia.

This waspfish looks more like a scorpionfish, with a dorsal fin that starts directly above the eyes. This is the only species in this genus that I have seen for sale. While coloration is said to be extremely varied, ranging from solid brown to rust red to pink and white, every specimen I’ve encountered was solid brown, with a white rectangle on the face.


You now have a good foundation for enjoying scorpaeniform fishes in your own aquaria, and you’ve had an overview of most of the species you will find for sale in the aquarium hobby. I’ve incorporated my more than 20 years of hands-on experience keeping these fishes into this book and shared with you, the reader, useful tips and techniques to help you succeed with them. I hope you will consider rising to the challenge of breeding these fishes in your tanks, and I wish you luck in discovering the secrets to successfully rearing the fry of these magnificent animals.

The long-spined waspfish is the species most often found in the aquarium hobby. It is an extremely slow feeder and strongly prefers live over prepared food.


A Scorpaeniform to Avoid

Stonefishes, species in the subfamily Synanceiinae of the family Synanceiidae, are the most venomous fishes in the world. People are usually envenomated when they step on a concealed fish, and they usually die. While all the other fish covered in this book are venomous and warrant extremely careful handling, their stings are not generally lethal. Stonefish, on the other hand, have no place in the aquarium hobby.

Excerpted from the book Lionfishes and Other Scorpionfishes: The Complete Guide to the Successful Care and Breeding of These Spectacular and Popular Marine Fish. ISBN 9780793816798; August 2010. © T.F.H. Publications Inc. Used with permission.

Posted October 21st, 2010.

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Book Excerpt: Clownfishes and other Damselfishes

Clownfishes and Other Damselfishes: The Complete Guide to the Successful Care and Breeding of These Hardy and Popular Marine Fish

Book Excerpt: Clownfishes and other Damselfishes
The Complete Guide to the Successful Care and Breeding of These Hardy and Popular Marine Fish

Jeff Kurtz

Pomacentrids purchased in good health are about as bulletproof as aquarium fishes can get. But the operative phrase here is “purchased in good health.” Unfortunately, these fishes may endure a lot of stress from the time they’re captured in the wild until they appear for sale at your local fish store. As a result, when many specimens reach your dealer’s shop they may be on the verge of succumbing to disease, injury, ammonia poisoning, or other stressors associated with collection and shipping.

Chapter 3: Choosing and Housing Pomacentrids

Signs of a Healthy, Happy Pomacentrid

A healthy pomacentrid will have a full, robust body with completely intact fins, vibrant coloration, and clear, non-bulging eyes. It should be swimming actively (though clumsily in the case of clownfishes) and behaving boldly. Most importantly, make sure the specimen is eating as it should. It is seldom difficult to elicit a feeding response from a healthy pomacentrid, so be sure to ask your dealer to feed the specimen right in front of you. If it doesn’t eat, pass it by. Period.

Avoid specimens that are listless and lethargic; cowering in the corner of the tank; twitching, trembling, or dashing about nervously; swimming erratically; breathing rapidly; or scraping their bodies against rocks, decorations, or other objects in the tank. Also avoid any specimen that exhibits faded coloration; any obvious injuries, pits, or lesions; ragged, torn, or rotting fins; excessive body slime; a velvety coating or tiny white spots; cloudy or bulging eyes; or a pinched-in belly. Essentially, if any physical or behavioral symptom gives you cause for concern, you’re better off bypassing the fish that exhibits them.

And don’t limit your health evaluation strictly to the specimen you want to buy. It’s important to pay attention to the condition of the other fishes that are sharing its tank, too. If you see other specimens in the same tank that are sick, dying, or dead, it’s a pretty safe bet that it won’t be long before the specimen you’ve got your eye on gets sick as well—even if it appears to be perfectly healthy at the moment.

A. ocellaris are tank-raised in large numbers for the aquarium hobby. This one has an abnormal pattern.

When selecting pomacentrids for your tank, pass over any that are lethargic, hiding, or uninterested in food.

Patience Is a Virtue When Purchasing Pomacentrids

Pomacentrids that spend a few days in a dealer’s tank getting acclimated to aquarium conditions and getting accustomed to eating standard aquarium fare before they are purchased tend to have a much better overall survival rate. So do yourself a favor and resist the urge to buy that damsel or clownfish on the same day it arrives. If you’re concerned that another customer will buy the specimen you want in the meantime, ask the dealer whether you can put down a little earnest money to hold the specimen for a few days so you can be sure it’s healthy.

Resist Those Tiny Discount Damsels!

It’s quite common for aquarium stores to offer very small damselfishes for sale at just a few dollars apiece. While these prices may seem like an excellent deal, those tiny discount damsels are really not such a hot bargain, after all—a truth that I had to learn the hard way.

Some years ago I was stocking a new marine aquarium and decided that a school of six blue-green chromis, Chromis viridis, would be a great way to introduce some activity and color to the tank. Imagine my delight when I discovered that a dealer in my area was offering blue-green chromis for the low, low price of just $1.99 each. They had just arrived that day, and I was first in line to buy them! How could I resist? Sure, they were only about a half inch (1 cm) in length, but they would grow, right? Besides, the larger specimens in an adjacent tank cost twice as much!

I took my six specimens home and acclimated them very gradually to my quarantine tank, still smug about my substantial dollar savings. The folly of my purchase started to become apparent the next morning when I found one of them dead. No problem, I thought to myself. I’ve got five chromis left—still enough for a small school. The next day, however, I was down to four. The day after that, only two remained. And then, the following morning, there were none.

The lesson I learned from that disappointing loss, one that has been confirmed many times by the experiences of other hobbyists, is that undersized damsels, however desirably priced they may be, have an absolutely abysmal survival rate because they are simply not resilient enough to endure the rigors of capture, shipping, and handling.

Buy Captive-Bred Clownfishes

On the freshwater side of the aquarium hobby, the vast majority of specimens sold on the market are bred commercially. But just the opposite is true on the marine side of the hobby. The number of species that are still wild caught far exceeds the number of those that are captive bred on a commercial scale.

There’s a good reason that so few marine fishes are being bred in captivity. The eggs and tiny larvae of most reef fishes go through a prolonged pelagic stage, during which they drift over many miles of sea with the planktonic rafts. Eventually they reach a stage of development at which they are ready to settle on a coral reef.

This reproductive strategy has the obvious advantage of distributing a species over a very wide range. But, as you might imagine, it also creates lots of headaches for aspiring breeders because little is known about how to sustain such minuscule larvae during this long pelagic stage. Even culturing a food small enough to fit into the tiny mouths of these larvae is problematic. On the other hand, many of the clownfishes are now being commercially bred on a routine basis.

Captive breeding of clownfishes is easier than it is for many other reef fishes because the clownfishes are demersal spawners (they lay their eggs on a substrate rather than in the water column), the larvae are fairly advanced developmentally when they hatch, and the larvae don’t have as prolonged a pelagic stage as many other reef fishes do. Because clownfish larvae are relatively large, they are able to accept easily cultured live foods, such as marine rotifers and, later, brine shrimp.

Whenever possible, hobbyists interested in purchasing a clownfish should choose captive-bred specimens over wild-caught specimens. This offers numerous benefits to the hobbyist. They include:

• Captive-bred clownfishes have not had to endure the rigors of capture and prolonged shipping, so they are in much better condition overall when they arrive at your local aquarium store.

• Captive-bred specimens are used to life in captivity—the only life they’ve ever known! There is no difficulty getting these fish to accept standard aquarium foods.

• Captive-bred clownfishes are less likely than wild-caught individuals to carry diseases or parasites.

• You can also be confident that you’re starting with a young specimen. There is no way of knowing whether a wild-caught specimen is just starting out in life or approaching the end of its natural lifespan.

Sometimes captive-bred clownfishes cost slightly more than wild-caught specimens, but they are well worth the price! Wouldn’t you rather pay a bit more for a specimen that is far and away more likely to survive in your tank and that wasn’t taken from the wild? Consider it an investment in success.

Deadly Harvest: A Note About Cyanide Collection

One very regrettable aspect of the marine aquarium trade is the ongoing use of cyanide poison to stun and capture reef fishes in some areas, such as the Philippines and Indonesia—and, yes, damselfishes (though, to my knowledge, not clownfishes) are among the fishes known to be collected in this manner from these areas.

Cyanide is used for the very simple reason that it facilitates the easy capture of large numbers of fishes with very minimal effort. The fish collector simply squirts the cyanide mixture into the coral heads and crevices where the fishes take refuge and then gathers them up after they become immobilized and sink to the bottom. Because cyanide collection is so much easier than net collection, fishes taken in this manner can be brought to market at a price that is much more attractive to hobbyists.

The problem is that virtually all cyanide-exposed fish perish—many right there on the spot and many more during transportation and distribution. Those that linger long enough to make it into a hobbyist’s tank die days or weeks later, leaving the hobbyist guessing what he or she could possibly have done wrong to cause the fish’s fatality.

What’s worse, cyanide collection doesn’t kill only fishes. It also wipes out any invertebrates that are exposed to the poison, which can lead to the loss of entire tracts of coral reef.

Unfortunately, there’s no way for the average hobbyist to know just by looking at the fishes in a dealer’s display tanks whether or not they were collected by net or via an unsustainable method such as cyanide poisoning. But there are steps conscientious hobbyists can take to ensure that they aren’t supporting this ecologically devastating practice. They include:

• Get to know the dealers in your area, and ask them about the source of their livestock. Better dealers should be able to tell you where their fishes come from (remember, fishes collected from the Philippines or Indonesia should be considered suspect) and whether or not they were collected in a sustainable manner.

• As mentioned earlier, purchase captive-bred fishes whenever possible. There’s obviously no risk that those specimens have been exposed to cyanide.

• Be willing to pay a few extra dollars for net-collected fishes. An inexpensive fish is no bargain if it dies shortly after purchase.

• If it is available in your area, purchase livestock that has been certified by the Marine Aquarium Council (MAC). MAC certification is your insurance that a fish has been collected, handled, and shipped in a sustainable fashion.

Some collectors use cyanide to catch damsels and other fish, a practice that threatens the survival of coral reefs. Avoid purchasing cyanide-collected fish.

Choosing a Tank for Pomacentrids Is No Big Deal

Having limited space in your home to accommodate an aquarium is not necessarily a limitation on keeping clownfishes and damselfishes. Many are well suited to life in a modest-sized home aquarium in the range of 20 to 40 gallons. Even tanks that would be considered grossly undersized for many other reef fishes can be suitable housing for certain pomacentrid species.

Nice for Some Nanos…

With the burgeoning popularity of nano aquariums—defined for our purposes as systems of 30 gallons or smaller—the demand has risen for marine fishes that can adapt to life in such confined quarters. Many pomacentrids, especially certain smaller clownfish species such as the ocellaris and percula clowns, can be considered reasonable candidates for these smaller systems.

Some of the smaller clownfish, such as ocellaris and percula clowns, will do well in a nano aquarium.

…But Not for All

Not all nano aquariums can realistically support a clownfish or damselfish for the long term. Don’t assume that just because one of these fishes can fit in a very small nano system that it will be healthy and happy there over the course of its life. Pomacentrids can live for well over a decade in captivity, and they deserve the best care we can provide over the course of that long lifespan. So we have to be realistic about the volume of water we attempt to keep them in.

Would a 20- to 30-gallon system suffice for a small to medium-sized pomacentrid, provided it is well maintained and appropriately stocked? Almost certainly. When you move into the 10- to 12-gallon nano range, you’re definitely entering borderline territory, although it could be done with meticulous maintenance and attention to water parameters. But a 5-gallon or smaller system? Consider these out of the question for even the smallest clownfish or damsel.

Nano Negatives

Because so many pomacentrids are good candidates for smaller aquariums, it behooves us to examine some of the drawbacks inherent in these systems. These challenges shouldn’t necessarily be viewed as deal breakers for the aspiring clownfish or damselfish keeper, but understanding that they exist is the first step toward overcoming them.


A smaller volume of water is far less stable than a larger volume in terms of its temperature, pH, specific gravity, etc. Changes for the worse occur much more rapidly in a nano tank than they do in a larger system. If the ambient air temperature shifts markedly upward or downward, the water temperature in a smaller volume of water will change much more rapidly than it will in a larger volume of water. Compare the respective cooling rates of a cup of coffee and a pot of hot water and you’ll get the general idea.

Water Quality

A modest amount of evaporation results in a significant increase in specific gravity in a smaller system. So forgetting to perform a freshwater top-off—even for one day—could cause a precipitous rise in specific gravity and have a very adverse effect on the well-being of the livestock in a nano system.

Additionally, any contaminants, such as soap or lotion on your hands, that are accidentally introduced or additives that are accidentally overdosed are much more concentrated in a smaller volume of water than they are in a larger volume.

Lack of Space

Furthermore, the smaller the aquarium, the easier it is to overstock or stock inappropriately. Giving in to the impulse to add “just one more specimen” can tax the biofilter in a system of any size, but in a small system, yielding to this temptation can have a disastrous impact on water quality.

Also, you have to factor in the relative aggressiveness of many pomacentrids when considering keeping them with other species or conspecifics in very confined spaces. If an aggressive damsel or clownfish takes issue with one of its tankmates (or vice versa) in a 100-gallon aquarium, the two can usually stay out of each other’s way, thereby minimizing territorial squabbles. But throw the two adversaries together in a 20-gallon tank and they’ll fight like two cats in a duffel bag because there’s simply no way for each to escape the other’s line of sight.

Again, this isn’t an attempt to dissuade you from keeping a clownfish or damsel in a smaller system (with the exception of really small nanos, which I would discourage), just to apprise you of the limitations of small systems and the special challenges they present.

Just Right for Reef Tanks

Corals and other sessile invertebrates are the priority in any reef aquarium. The number of fishes is often kept low in order to minimize their impact on water quality, which must be topnotch in a reef system, and any fish specimens that are introduced are chosen for their compatibility with the invertebrates—i.e., they don’t include sessile invertebrates as part of their natural menu and they aren’t heavy polluters. Many clownfishes and damselfishes satisfy these reef-compatibility requirements superbly, being generally small in size, producing minimal waste, and usually being inoffensive to sessile invertebrates.

Of course, there are exceptions to every rule. For example, the big lip damsel, Cheiloprion labiatus, would not be a good candidate for a reef system containing Acropora spp., as it feeds primarily on the polyps of those corals. For another, the bowtie or black damsel, Neoglyphidodon melas, can’t be trusted in a reef system stocked with soft corals, as they compose its natural diet. But most of the commonly sold pomacentrids are generalized omnivores that can be trusted around corals and other sessile invertebrates. If you do your homework by researching the needs of any clownfish or damselfish specimen before you bring it home, you should have no problems in this regard.

All clownfishes are reef-safe in the sense that they won’t nip at or eat polyps; however, as we’ve already touched upon, they may irritate sessile invertebrates that they’ve adopted as surrogate hosts, preventing them from expanding their tissues to receive the light they need to sustain themselves. In some cases this can prove deadly to the invertebrate, so if this behavior is observed and it continues unabated, the offending clownfish will need to be removed from the reef system.

Many of the pomacentrids are good candidates for reef systems, being relatively small fish that won’t eat corals, anemones, or other desirable invertebrates.

The bowtie damsel is one of the species not safe for reef tanks because they will eat soft corals. This is a juvenile; the adults are solid black in color.

Aquascaping the Pomacentrid Aquarium

Whereas some reef fishes demand ample open space for swimming in an aquarium, clownfishes and damselfishes seem to do best when they have lots of structure in which to take refuge. Clownfishes, absent a host anemone or suitable surrogate, will often adopt a small cave or ledge as a safe retreat. Hence a tank containing pomacentrids should be aquascaped to provide lots of nooks, crannies, crevices, and caves.

Gnarled porous live rock is the ideal choice of aquascaping material, as you can stack it in a greater variety of configurations than you can slab-like rocks. You can also join these live rocks together with plastic cable ties or aquarium-safe epoxy or silicone to enhance stability or to create more elaborate aquascaping—such as bridges or overhanging ledges.

Artificial branching stony corals would provide a nice naturalistic setting for species that naturally seek refuge among coral heads, such as the popular humbug damsel, Dascyllus aruanus, and its very similarly patterned cousin, the black-tailed humbug, Dascyllus melanurus.

As far as substrate goes, crushed aragonite or crushed coral is just fine for pomacentrids. Clownfishes and damsels aren’t burrowers, so it’s not necessary to provide them with a deep sand bed (DSB) unless you plan to utilize one for the combined purpose of nitrification and natural nitrate reduction. A substrate depth of 2 inches (5 cm) is more than adequate if you just want the tank to have a naturalistic look. For a DSB, a minimum depth of 4 inches (10 cm) is recommended.

For easier maintenance and to minimize the amount of debris that gets trapped in the substrate, where it can decompose and quickly foul the water, many hobbyists who keep nano systems prefer to use no substrate whatsoever. Or, if they want the naturalistic appearance of a crushed aragonite or coral substrate, they might choose to use a faux substrate by gluing a fine layer of substrate material either to the bottom of the tank or to a sheet of glass or acrylic that has been cut to fit the bottom of the tank.


The Perfect Introduction to Saltwater Aquariums

Not only are many pomacentrids great fish for novice marine aquarium hobbyists, but they’re also a good choice for introducing kids to the responsibilities of marine fish keeping. A smaller aquarium containing a damselfish or, perhaps, a clownfish pair can be set up and maintained with a little parental oversight. After some basic instruction, kids should be able to manage everyday chores, such as feeding, checking the water temperature, and topping off the tank with dechlorinated tap water to compensate for evaporation. Initially, the parents might want to help with some of the more complicated tasks, such as testing for ammonia, nitrite, and nitrate and performing water changes, but even these chores can eventually be learned and mastered by children once they’ve had an opportunity to observe how they are accomplished. Such a family aquarium is a great educational tool that will help strengthen a child’s sense of responsibility—not to mention it may just awaken a lifelong passion for the marine aquarium hobby!

Small Pomacentrids in Big Tanks

Introducing a very small pomacentrid to a very large tank can pose certain husbandry challenges that won’t necessarily present themselves when the specimen is in your quarantine tank. These challenges might include certain dangers that weren’t an issue in quarantine and that are never experienced in nature. For example, a diminutive damsel can easily be swept into the overflow chamber of a wet/dry biofilter or get stuck on the intake of a powerhead. Any such hazards must be blocked or screened off to prevent accidents.

The high level of water movement that is necessary in a large system can also create problems for a small pomacentrid. Constantly struggling against a very powerful current can exhaust a little damsel or clownfish—potentially stressing it to the point of death. Also, feeding small pomacentrids is more of a challenge in a larger system because the brisk water movement can quickly disperse small food items before the damsel or clownfish sees it. To mitigate these potential problems, it’s helpful to provide an area of slack current in the aquarium where the clownfish or damsel can rest and take refuge. To prevent tiny food items from dispersing too quickly, it’s a good idea to temporarily unplug your powerheads and pumps at feeding times.

Excerpted from the book Clownfishes and Other Damselfishes: The Complete Guide to the Successful Care and Breeding of These Hardy and Popular Marine Fish. ISBN 9780793816781; April 2010. ©T.F.H. Publications Inc. Used with permission.

Posted October 21st, 2010.

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Book Excerpt: Catfishes

The Complete Guide to the Successful Care and Breeding of More Than 100 Catfish Species

Book Excerpt: Catfishes

The Complete Guide to the Successful Care and Breeding of More Than 100 Catfish Species

Lee Finley

The variety found among catfishes is nothing short of amazing. While on any given visit to your local aquarium store you might see a reasonable selection that most likely will be heavy on South American Corydoras and loricariid (plecos) species, over time you’ll begin to grasp the great amount of other catfishes that exists. Many species are seasonal in their hobby appearance, and new species (or old ones that haven’t been imported for some time) are constantly becoming more available. When the whole picture is put together, you’ll see what makes this group so desirable and attractive to so many aquarists.

As you work your visual way through the catfishes available to you, it’s good to try to learn as you go. You obviously won’t be purchasing all of the catfishes that you see, but you should take mental notes on at least some of those species and try to research them. This will set the stage and make you better prepared should you at some time see a particular species again and say, “I’m going to take some of those (or that one) home.”

With many groups of catfishes you can deal more or less in generalities. A great many of the  Corydoras species, a South American group, will fall into this niche. But generalities may not always be successful, and you will have to make, for example, some differentiation between the more standard Corydoras species (C. aeneus, C. delphax, C. paleatus, etc.), and the genus’s smaller mid-water swimmers, such as C. pygmaeus and C. hastatus. Likewise, generalities apply also to the popular Synodontis species. As a group these African catfishes adapt exceedingly well to aquarium life, but you must make decisions in regard to the size range that you would like to maintain—4 inches (10 cm) or 1 foot (30 cm)—and the behavioral characteristics that you are looking for. Do you want a model catfish for a peaceful tank or a species that’s tough enough to hold its own with a batch of rowdy tankmates? If you’re at least partially armed with such information, you’re already on the way towards success with a chosen fish. Of course, not every  catfish can be easily known or  figured out, but as long as you do your best conferring with various literature sources (paper and electronic), other aquarists, and store personnel, you have embarked on the proper path.

Peppered Cory

C. paleatus¸ usually sold as the peppered cory, is a commonly available cory cat. It is one of the easiest species to keep and breed.

Three Important Traits to Consider

As I’ve already mentioned, there are three major areas in the pursuit of catfish knowledge that are very important in your preparatory stages. Of course, there are numerous other aspects as well, and many of those aspects will be looked at as we move along.


The first area is that of  behavior. If you have a tank of peaceful fishes and wish to add an interesting catfish or two, the last thing that you want is to add a species that’s going to upset the pastoral pleasantness that you’re enjoying. As an example, there are two Synodontis catfishes that are at least superficially similar in appearance—S. congica and S. notata. Both have a silvery to grayish body coloration and are adorned with varying numbers of round black spots on their sides. S. congica would be a model catfish for such a peaceful tank. S. notata, although not a terribly destructive catfish, can be more than a bit boisterous, especially as it grows. S. congica is pretty much always going to be peaceful. The same cannot be said with certainty about S. notata.

Synodontis notata may be too active and rambunctious for many hobbyists, but other Synodontis species are more peaceful.


Trying to figure out who might eat who also needs consideration. This might sound a little flip, but it’s truly a serious consideration. Many catfishes eat other fishes, and their capacities in this regard can be downright amazing at times. Many years ago, when I was predominately a cichlid keeper, I had a couple of tanks of various catfishes. On one shopping trip I returned home with a cute pseudopimelodid, Batrochoglanis raninus, that was about 3½ inches (9 cm) long. I knew that this large-mouthed species had a reputation for eating smaller fishes, so I chose its tankmates carefully. The smallest fish in the tank was a nice South American whiptail cat, Rineloricaria sp., that was about 5½ inches (14 cm) long. No problem, right? Wrong! The following morning I went down to the fishroom and was greeted with an amazing sight. Protruding from the new fish’s mouth was about 3 inches (8 cm) of the rear end of the whiptail cat! Over the next few days the whiptail disappeared into the pseudopimelodid. I wasn’t amused, but I did learn an important lesson—never underestimate what a predatory catfish might be able to swallow.


Lastly I must say a word about the potential size of catfishes intended to be kept in home aquaria. Some simply don’t belong in home aquaria; they get too big or too nasty or both. This is my personal opinion, and I do feel some discussion on this is necessary.

As might be expected of a group of fishes containing over 3,000 species, there are some very large catfishes. Large is, of course, a subjective word, and I take it herein to mean in relation to the size of the containers (aquaria) that we keep our fishes in. To set the stage for the following I will note that the catfish group of fishes also contains an amazing number of species that are small to medium-sized (say 1 foot [30 cm] or less) and are therefore more or less ideal to acceptable inhabitants for the home aquarium. (A lot depends on the size of your aquarium, obviously—many aquarists would consider a  foot-long fish to be a good deal bigger than “medium-sized.”) There are quite a few that get a bit larger than this but, based on their mild deportment and habits,  can still be considered for keeping in big tanks if that’s your cup of tea.

If there’s a poster cat for large catfishes not belonging in aquaria it’s surely the South American redtail catfish, Phractocephalus hemioliopterus. At a small size (2 to 3 inches [5 to 8 cm]) this colorful pimelodid is almost irresistible. It pretty much has everything going for it: color, interesting appearance, and personality. But things can turn sour when you realize that this catfish eventually reaches a total length of almost 4½ feet (1.4 m)! If anything else is needed to cap this, a healthy redtail of this size weighs in at about 100 pounds (45 kg).

What is the home aquarist to do with a fully grown redtail, or even one that attains between half and three-quarters of the maximum size, which is still an enormous fish? The potential problem is actually twofold. The first scenario is maybe the worse of the two. This is where an unknowing, and often newer, aquarist purchases a small redtail without knowing its size potential. Or, worse, even knowing it goes ahead with the purchase. This will eventually lead to an unhappy catfish and an owner of equal sentiment. Sometimes a store might take the fish back, but this isn’t a certainty. What then? Will the fish languish and eventually die in cramped and environmentally poor conditions? Will it be euthanized? Will it be released into local waters? None of these outcomes is acceptable and/or fair to such a potentially magnificent catfish.

Certainly at least some dedicated aquarists like to keep large fishes. While such aquarists have large tanks for their charges, it’s impossible in a realistic sense to provide a big enough tank for an adult redtail catfish unless something akin to a public-style aquarium is built in one’s home. Extremely rare are even the most dedicated of aquarists who might be willing to go this necessary extra mile.

I could list many other catfishes and note the potential sizes that they might reach, but hopefully by now you’ve gotten the point. If you’re new to catfishes, research your purchases and make sure that you’re ready to proceed. If you’re a large-fishes aquarist, start saving up for that new large tank!

Although it is beautiful and commonly available, the redtail catfish grows too large for all but the most dedicated hobbyists and the biggest tanks.

Making Your Decision

The potential last step of the buying process is to purchase or not to purchase any of the catfishes that you see. Although the store workers can assist you in such decisions, in the end you’re the final arbiter. Aquarium stores don’t want to sell you sick fishes, as this will not be good for their business in the long run. But, again, you have the final say with your purchases, and extra vigilance regarding them will benefit you greatly.

Pick from a Healthy Tank

First, you want to look around a store tank and make sure that it has healthy-looking fishes. If one fish, of any kind, has what might be a spreadable condition or disease, move on. This isn’t a tank that you want to choose fish from. Most stores will recognize such problems and quarantine the tank, but you should do your own overview just to be sure.

You should give any potential purchase a good visual going over. With this you should carefully consider both the positive and negative aspects of the particular catfish. This should include a basic health check regarding the physical condition and close observation of the behavior exhibited by the fish. With many catfishes this might present some initial problems in that they may very well, after their travel, be more of a mind to hide away among the tank’s decor than to present themselves to you for inspection. Here is where store personnel can be helpful by gently going into the tank with a net or other object and making sure that you can get a good look at your potential purchase.

Physical Appearance

For general physical conditions, you will want to make sure that the catfish has no bloody areas on the body or the fins (especially at the edges). Also look for any fuzzy patches that might indicate a wound that will lead to a subsequent fungal infection. Such funguses often appear at the ends of the dorsal or pectoral spines of many catfishes. They aren’t an immediate threat, but if you do purchase such a catfish you will then be responsible for taking the appropriate actions to treat the infection. You will also want to look closely at the body to make sure that there is no thin grayish/whitish coating, which might be indicative of an external bacterial infection. The eyes are a good place to check extra close for this. Many catfishes will show a deep reflective appearance, but this is normal. Some catfishes, such as talking cats (doradids), may normally show a whitish cast to the eyes and body (especially the head area), but with some experience you can easily differentiate this condition from a potential bacterial infection.

Parasitic infections also need to be considered. Ich, also called white spot disease, is one to watch for, especially during cool-to-cold times of the year. In one stage of its life cycle the parasite shows as small scattered white spots on the body and fins of an infected fish. Some driftwood catfishes (auchenipterids), such as Auchenipterichthys coracoideus, show a definite pattern of small white spots on their bodies. While these spots may superficially resemble ich, the regularity of the pattern—as opposed to the randomness of ich—is the tip-off that the spots are normal.

The barbels are another area to check out. Try to make sure that they are not shortened, bloody, or missing. You can compare the barbels of a fish you’re interested in against those of an ideal specimen  if you’re familiar with the species, or you can compare the fish with others of the same species in the tank.

Thinness: Many catfishes, especially those that have recently arrived at a store, may often be quite thin. This is common, as feeding is often quite light along the various stages of transit. Thinness is normal, but there are extremes to the situation that are best avoided. This situation is especially notable with various loricariids. Because  these catfishes usually stay close to the substrate it can often be difficult to get a good look at their abdominal areas. It’s a good idea to get a store worker to net a potential purchase from among these fishes so that you can get a good look at the fish’s underside. Some thinness is acceptable, but if the stomach area is heavily caved in you might want to consider coming back later, after the fish is settled in and eating, before making a purchase. Another area to check on loricariids is the eyes. Beware if the eyes are sunken into the head, below the rim of the eye socket. This is often a sign of severe starvation, usually coupled with a noticeably caved-in abdominal area. While loricariids in this condition might be brought back into good health with proper feeding, this cannot be considered a sure thing, and generally speaking such a catfish should be avoided. There are some loricariids, such as the royal pleco, Panaque nigrolineatus, that can actually pull their eyes down into the socket, but this is a form of protection, and the eyes don’t stay sunken for very long. If you see such a royal pleco in which the eyes are sunken, and remain so, you will be better off avoiding it and waiting for another one.

Carefully inspect any catfish before you buy it, paying special attention to its barbels.

The royal pleco can pull its eyes down into their sockets for protection, but avoid any individual with eyes that stay sunken.

Behavior in the Seller’s Tank

How catfishes are behaving is another important consideration. Observe their breathing to make sure that it’s normal. A steady respiration can be judged by observing the movements of the mouth and their gill covers. A rapid respiration observed on a resting catfish can often be a sign of a bacterial or parasitic infection on the gills or some other form of physical stress.

Also observe how a fish holds itself in the water. Here you do need to know something regarding the behavior of a particular species or group of species. For example, take some of the standard Corydoras species such as C. aeneus, C. paleatus, and many of the spotted forms that may collectively be sold as C. punctatus. These are primarily bottom-based catfishes, and if you see them hanging in mid-water or at the surface, you can be assured that there’s a problem of some sort. It could be poor water conditions in the tank, but it could also indicate some type of organic problem. In either case, these sick fish shouldn’t be brought home. These Corydoras should be actively moving around the lower part of the tank, with the occasional dash to the surface to grab a bubble of air (which they swallow and extract oxygen from in their gut). On the other hand, there are some Corydoras species that spend more time away from the bottom. Members of the C. elegans complex (C. elegans, C. napoensis, etc.) often fit into this group. And some of the smaller cories, such as C. pygmaeus and C. hastatus, are normally mid-water swimmers. If these diminutive species are lying on the bottom, or are swimming around near the surface in a dopey fashion, it’s not a good sign, and they should be avoided.

Additional Sources of Catfishes

One additional area that needs to be touched on is the purchase of catfishes that you can’t see in advance. Previously this type of business was generally done by mail or via the telephone, but the Internet and e-mail are now more typically the methods used for communication. There is nothing wrong with purchasing catfishes in this way. Many of the specialty dealers will often have a much wider variety of hard-to-find catfishes in stock than you might usually find at your local stores. But this availability does come with the fact that you can’t see the catfishes beyond a digital photo or possibly a short video. In cases of purchasing catfishes by this method it’s better to use the phone and talk with the party or parties involved. A short phone call can provide good information on the potential purchase much better than an e-mail can. That is my opinion and I’ll stand by it. A phone call is also much better for developing a relationship with such a provider.

A more recent method of obtaining catfishes also comes to us via the Internet—the purchase of catfishes by auction. While some aquarium fishes have been seen for some time on larger Internet auction sites, the specialty sites are a bit newer, and some of them serve as a platform for the auctioning of an amazing amount of fishes—catfishes included. I haven’t personally obtained any catfishes by this method, so I cannot offer specific comments beyond, as mentioned earlier, working on developing a good rapport with the source.

Going Home

I’m returning you now to your local store and your recent purchase. Your store will bag your fishes, and many stores will use a double-bag method for most catfishes. This is good practice, but for certain species, such as the larger Synodontis, it is rarely sufficient. Such catfishes, with their large pectoral fin spines, will often need three or more bags. And even with this, a quick movement by the fish will easily send a pectoral spine right through the multiple bags. For moving such catfishes I would suggest using a plastic bucket with a cover. It’s always good to have some of these buckets handy. Most stores have them and will probably be happy to lend you one if necessary. Another way of moving larger catfishes is with a large shipping bag (stores will also have these on hand) inside a rigid foam shipping box. Catfishes are moved all over the world like this—why not to your home from the store?

During those times of the year when it’s too cold or too hot, it’s best to have an insulated container into which you can put your bagged catfish. Rigid foam fish shipping boxes, often enclosed within a cardboard box, are ideal for this purpose; usually your store can supply you with one for a minimal charge. Likewise, you can also carry a picnic-style cooler along with you on shopping expeditions. This little bit of extra protection is well worth having.

What Topics to Research

When researching the catfishes that interest you, look first for information on their  behaviors, diets, and full adult sizes; look also for recommendations about potential tankmates, if such recommendations are made. These topics can help you decide whether the catfishes would do well in a small community tank, a tank devoted to large fishes, or a single-specimen tank.

The Journey
to Your Tank

The journey made by most wild-caught catfishes to your home tank is often a long one: from the  collector of the fish in its native waters  to the exporter, then from the importer to  the wholesaler and then to your local store and then lastly to your tank. Breeding of catfishes by commercial breeders and  local hobbyists forms an important exception to this pathway. Although there is an increasing variety available, most domestically bred catfishes will consist of some loricariids (e.g., Ancistrus spp.) and various Corydoras. Another group often available is some of the Lake Tanganyikan Synodontis species, such as S. lucipinnis and
S. multipunctata.

Most catfishes offered for sale come from the wild, from fish farms in Florida or Southeast Asia, and from breeders in eastern Europe. Some of the fishes from this last-named source, however, are hybrids (see the Synodontis section in Chapter 5).

The Catfish-Barbel Connection

Catfishes are famous for their barbels. In fact, the order Siluriformes, to which all of the catfishes belong, got its common name from the fishes’ barbels. They almost look like a cat’s whiskers. Other freshwater fishes, including carps, arowanas, and loaches, also have barbels, but usually the first fish that comes to mind when a hobbyist hears the word “barbel”  or “whiskers” is a catfish. Catfish barbels vary in length from species to species. Cory cats have small barbels to match their small size, while others, such as Sorubim lima and Pimelodus spp., have barbels that are several inches long.

Taken from the book Catfishes: The Complete Guide to the Successful Care and Breeding of More Than 100 Catfish Species. ISBN 9780793816774; October 2009. © T.F.H. Publications, Inc.  Used with permission.

Posted October 21st, 2010.

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