Author: Mark Denaro
Butterflyfish have been labeled as difficult to keep, but this professional fishkeeper explains that may not be the case. He offers his top 10 species that adapt to aquarium life with ease and make hardy additions to marine tanks.
The butterflyfish of the family Chaetodontidae are regarded as some of the most beautiful marine fish. While their colors may not be as gaudy as those of the angels or tangs, their patterns are frequently quite interesting, consisting of combinations of lines and spots that provide a subtle beauty. The typical pattern includes a vertical stripe through the eye for disguising position and fooling predators. Many species have an ocellus (eye spot) on the back or in the soft dorsal fin to further the illusion that the head is at the posterior end of the body.
Butterflies exhibit a wide array of feeding strategies. Some species are generalized feeders and are, consequently, fairly easy to maintain in captivity, while others are highly specialized feeders that will not readily adapt to typical aquarium fare. In fact, many species feed exclusively on coral polyps and, in some cases, may be so specialized that they feed only upon the polyps of one genus, or even one species, of coral. Animals with specific dietary requirements that cannot be met by the vast majority of aquarists are best left on the reef.
Even if we eliminate these species from consideration as aquarium inhabitants, we still have an extensive list of suitable species to consider. The vastly different requirements and suitability of these species make it critically important that you research any specimen you are considering prior to purchase. Unfortunately, the fact that a particular species is offered for sale in your local shop or through your preferred online vendor does not mean that it is suitable for maintenance by an aquarist with your level of experience or even in an aquarium at all.
There are some generalizations that can be made about the butterflies. They will seldom display any aggression toward members of any other family. On the flip side, they are not typically the recipients of aggressive behavior from members of other families. Like all other species, they do exhibit a fight-or-flight response when threatened. Their fight response consists of fully raising the dorsal fin, tilting the body in a head-down position, and pointing the dorsal fin at the aggressor. The leading dorsal fin spines are elongated and make an impressive, intimidating display.
While most aquarists keep butterflies as single specimens, I find it far more interesting to keep them in pairs or in small groups. Every species of the genus Chaetodon that I’ve kept in pairs has worked out well, particularly with small- to medium-sized individuals. The exceptions are members of the genera Chelmon and forcipiger, which are somewhat quarrelsome with each other, though they get along well with butterflies from other genera.
Sex determination in several species of Chaetodon studied to date indicates that they are gonochorists, or have predetermined sexes. This does not explain why a random selection of two fish from a group of young individuals seems to result in a bonded pair, which will spend quite a bit of time together in the aquarium. Could it be that there is some schooling drive that explains this or that there are more factors at work in sex determination than have so far been discovered? Only future research can answer these questions. Top 10 Chaetodon Species
The Genus Chaetodon
The species included here are all members of the genus Chaetodon. As currently constituted, this is the largest butterfly genus. It contains a number of subgenera, and it is possible that some or all of these will be raised to genus status in the future, but that is a question for the ichthyologists and doesn’t affect our ability to keep and care for them.
Most species suitable for aquarium maintenance will accept the usual assortment of frozen foods within two days of arrival. Specimens that prove finicky can usually be tempted to eat by offering fresh human-consumption-grade clams or mussels. Simply open the shell and drop them in the tank. Salad or popcorn shrimp (the unbreaded kind!) may prove persuasive too. In extreme cases, dropping the salinity to 1.018 or lower will sometimes prompt them to begin eating. Most butterflies are not suitable reef tank inhabitants, as they feed on invertebrates. Several species can be kept in reef aquaria, but this usually requires some compromise, as there will almost always be at least one desirable invertebrate that these species eat. Very rare is the butterfly that can resist eating feather duster worms, for example.
Choosing the Best Butterflyfish
The following ratings are based on my experiences with these fish. I have at least some experience with approximately 65 to 70 species in the aquarium. Unfortunately, those numbers include many obligate coral feeders and none of those are suitable. Because many of the butterflies have a fairly broad range and the collecting methods and shipping times vary, it is entirely possible that your experiences will differ from mine.
There are a number of species that are considered easy to maintain by some and difficult to maintain by others. A few good examples of that are the redtail butterflyfish (C. collare) and the latticed butterflyfish (C. rafflesii). I’ve had very good luck with both of those, but many other writers have had poor survival rates with them. I’ve tried to avoid adding species like that to this list. There may be other factors that influence success, including the number kept. C. collare in particular seems to do better when kept in pairs or groups rather than as a single specimen. Due to the widely varying experiences with such species, though, I felt it was best to leave them off the list. Color played a factor in creating this list, but I was more concerned with ease of maintenance. Price was not considered, and there are several rather expensive fish included along with some of the least expensive species.
1. Klein’s Butterfly (C. kleinii)
Klein’s butterfly (C. kleinii) is a relatively small species, growing to approximately 6 inches in length. It ranges throughout the Indian Ocean and Western Pacific, extending eastward to Hawaii, with the best specimens originating in Hawaii. C. kleinii feeds on a wide variety of invertebrates as well as algae. It also acts as cleaner fish, and, in some locations, specializes in cleaning shark bites on manta rays.
The basic color pattern is a brownish yellow on the body and unpaired fins. Small blue spots run in horizontal rows along the body. There is a dark vertical stripe from the nape through the eye to the chest. Above the eye, the stripe is bluish. From the eye to the chest, the stripe is black. In front of the stripe, the face is a tannish white. There can be light-colored, broad vertical bands on the body. These are not always present, and there can be either one or two. Klein’s butterfly readily accepts almost all prepared foods, especially frozen foods. Its diet should include some dry food and some algae-based foods. The more varied its diet, the healthier and happier the fish.
2. Lemon Butterfly (C. miliaris)
The lemon butterfly (C. miliaris) is a very close second. The primary range of this species is the Hawaiian Islands, where it is the most common butterfly and occurs in large aggregations. It feeds primarily on zooplankton but also engages in cleaning behavior on large fishes.
The base color of the lemon butterfly is, not surprisingly, yellow, though some individuals exhibit more of a yellowish-white color. Overlaid on the yellow are vertical stripes of black to dark brown spots. There are two sizes of spots, but all spots within a stripe are approximately the same size. This species also sports a black line from the nape to the base of the gill cover and a black caudal peduncle. Lemon butterflies can reach a length of 5 inches.
C. miliaris is a schooling species, and I prefer to keep more than one individual in an aquarium. Single specimens will adapt quite well, but this species’ behavior is more interesting when two or more are kept. Lemon butterflies are usually avid eaters and will take almost any food offered by the aquarist. They will usually begin feeding within minutes of being added to the aquarium.
3. Dot-and-Dash Butterfly (C. pelewensis)
C. pelewensis is one of the species commonly referred to as the dot-and-dash butterfly. The dot-and-dash butterfly has a silvery chest that transmutes into a bright-yellow color toward the rear of the fish. There is a series of diagonal spots and lines on the body. A thin orange vertical band runs through the eye. The caudal peduncle is orange. The body color and pattern continue into the fins. The dorsal and anal fins have a dark stripe with a yellow outer margin. C. pelewensis ranges throughout the Central and Western Pacific. Most of the individuals in the aquarium trade are collected in Fiji.
C. punctatofasciatus is a closely related species, and mixed pairs have been observed where their ranges overlap. In my experience, it is not as hardy in the aquarium, though it is still a good choice for those who’ve had some experience with other butterflies. C. pelewensis feeds on a variety of invertebrates in nature and adapts readily to the typical mix of aquarium foods. It is a relatively small butterfly, growing to 4 inches in length.
4. Merten’s Butterfly (C. mertensii)
Merten’s Butterfly (C. mertensii) is a member of the pearlscale species complex, most commonly represented in our tanks by the pearlscale butterfly (C. xanthurus). Other species with a similar appearance include C. madagaskariensis and the Red Sea endemic C. paucifasciatus. Overall, I’ve had good experiences with the three species I’ve kept, C. mertensii, C. paucifasciatus, and C. xanthurus, but have found C. mertensii to be the hardiest and most adaptable to aquarium conditions.
Merten’s butterfly can be found in the Western Pacific from Japan to Australia and east into the Central Pacific. Most of the individuals that are collected for the aquarium trade originate in Fiji. This species generally inhabits the clear waters of coastal reefs and outer reef slopes. It feeds primarily on small invertebrates and algae along with some coral polyps. Merten’s butterfly adapts readily to the aquarium and quickly accepts all of the standard aquarium fare. It grows to 5 inches in length.
5. Threadfin Butterfly (C. auriga)
The threadfin butterfly (C. auriga) is one of the most commonly available butterflies to the marine hobbyist. It has a broad distribution that covers most of the Indo-Pacific and the Red Sea. The Red Sea specimens differ slightly, and I suspect that, at some point, they will be described as a separate species. Juvenile threadfin butterflies sport an eye-sized black spot in the soft dorsal fin. The Red Sea specimens lose this spot as they grow, but those from all other areas keep this spot throughout life. Most of the fish that reach our tanks are collected in the Philippines or Indonesia. For some reason, most of the C. auriga collected in Hawaii are larger individuals and, consequently, more expensive due to increased shipping costs. If you need a larger fish for a display tank, the Hawaiian fish are well worth the price, as they are almost invariably in excellent condition.
This species does get large and can exceed 9 inches in length. Threadfin butterflies have a very cosmopolitan palate and will eat anything from small benthic invertebrates to shrimp, worms, coral polyps, plankton, and algae. Consequently, they generally feed very well and start to eat very quickly in captivity.
6. Raccoon Butterfly (C. lunula)
Much of what you just read about C. auriga also applies to the raccoon butterfly (C. lunula). The biggest difference is that the fish from the Red Sea are a different species in this case, C. fasciatus. Most of the fish available to the hobbyist are collected in the Philippines and Indonesia, with generally larger individuals available from Hawaii. Some hobbyists add C. lunula to reef aquaria as a natural predator on Aiptasia anemones. This typically works very well, though the raccoon butterfly may also eat desirable invertebrates, such as feather duster worms.
On the reef, raccoon butterflies feed on a variety of small invertebrates and algae and have been known to eat coral polyps, so careful observation is necessary if this species is added to a reef aquarium. Raccoons eat very well in captivity and will accept most of the standard aquarium fare with gusto. They can grow to about 8 inches in length.
7. Pacific Double-Saddle Butterfly (C. ulietensis)
The Pacific double-saddle butterfly (C. ulietensis) is also frequently sold as the falcula butterfly or false falcula butterfly. This species is very similar to C. falcula but can easily be distinguished by knowing the collection point or by looking at the color on the dorsal fin and body between the two black saddles on the back. In C. ulietensis that area is white, while it is yellow in C. falcula.
The Pacific double-saddle butterfly is found in the Central and Western Pacific and extends into the Indian Ocean as far as Christmas Island. Most aquarium specimens are collected in the Philippines or Indonesia. C. ulietensis is usually found on reefs with a rich growth of corals where it feeds primarily on algae and the tiny invertebrates that live in the algae. It quickly adapts to captive fare and can reach a length of 6 inches.
8. Indian Ocean Double-Saddle Butterfly (C. falcula)
The Indian Ocean double-saddle butterfly (C. falcula) grows slightly larger than C. ulietensis, reaching up to 7 inches in length. As its common name suggests, this species ranges throughout the Indian Ocean from the east coast of Africa to Indonesia and from India south to Western Australia. It is not as readily available as C. ulietensis, but its beauty and hardiness make it worth a little effort to find specimens. Most of the fish in the aquarium trade are collected in the Maldives or Sri Lanka. Like C. ulietensis, C. falcula feeds primarily on algae and the small benthic invertebrates that call the algae home and will typically accept prepared foods with little or no fuss.
9. Tinker’s Butterfly (C. tinkeri)
Tinker’s butterfly (C. tinkeri) is a particularly striking species that can reach 6 inches in length. Tinker’s butterfly is a deepwater species generally found at depths in excess of 125 feet. Its deepwater home combined with its colorfulness and hardiness all contribute to making this the most expensive fish in this countdown. Care must be taken to properly decompress the fish as it is raised to the surface or it will suffer swim bladder problems. This species is found in the Marshall Islands, Cook Islands, and Hawaii.
To the best of my knowledge, all the individuals offered to aquarists originate in Hawaii. It feeds on plankton, benthic invertebrates, and occasionally on coral polyps, and every specimen I’ve ever dealt with has taken prepared foods very quickly. C. tinkeri will do best in a tank with plenty of hiding places and somewhat subdued lighting. If this species fits into your budget and you have a tank large enough to adequately house it (75 gallons at minimum, but ideally 200 gallons or more), then by all means give it a try. I have kept pairs of this species, and they do quite well. I would suggest a minimum tank size of 200 gallons for a pair. The tanks I’ve maintained pairs in have all been 300 gallons or larger.
10. Bluecheek Butterfly (C. semilarvatus)
The bluecheek butterfly, or golden butterfly, (C. semilarvatus) is the largest fish in the countdown. The scientific literature lists its maximum size as 9 inches, but back in the early 1990s, I saw one at an importer’s facility in Chicago that was every bit of 17 inches in length. I had no idea that this fish could reach that size and have never seen another one that even approached it. This species also has the distinction of having the largest percentage of coral polyps in its natural diet of any species included here. In addition to corals it feeds on small benthic invertebrates in its natural habitat of the Red Sea. It is almost surprising that it feeds so well in the aquarium, but I’ve never had any trouble getting C. semilarvatus to accept the usual range of prepared foods.
The color pattern is yellow with some orangey-gray vertical bands that make the fish appear grooved, so it is quite unique in appearance. The gill cover and the area around the posterior half of the eye is blue, leading to one of its common names. Two or even a small group of these can be a tremendous addition to a large aquarium. Obviously, the more you want to keep, the bigger the tank must be. One of my old aquarium maintenance customers had a group of five in a 400-gallon tank, and that was one of my favorite tanks to observe.
Other species that I have had mostly good experiences with are C. burgessi, C. capistratus (particularly with small- to medium-sized specimens, and definitely better luck with a pair or small group), C. decussatus, C. mesoleucos, C. ocellatus, C. pictus, C. rafflesii, C. sedentarius, C. striatus, C. vagabundus, and C. xanthocephalus, along with the others that were mentioned while discussing the fish that were included in the countdown.
One of the criteria that I use to judge marine shops is the selection of butterflies that they offer. Many shops carry only a few species, and it is not uncommon to find shops that seldom stock them. I find that to be a real shame, as these are such wonderful aquarium fish. I believe it is frequently a case of throwing the baby out with the bathwater, in that people assume that because some species cannot be kept in the aquarium, none of them are suitable. As we’ve seen, that is just not the case.
You may need to expend some effort to find them, but they will reward you with great color, interesting behavior, and ease of care. When choosing your butterflies, look for clear eyes and good body weight, i.e., no pinched backs! The fish should be alert and aware of their surroundings, including you. If they’re picking at the bottom and the decor, that’s even better, as this usually indicates that they are already feeding or are about to start.
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