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Book Excerpt: Tetras and Barbs

by TFH Magazine on January 10, 2012 at 1:45 pm

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 in Uncategorized by TFH Magazine on January 10th, 2012 at 1:45 pm.

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