Changing coloration between juvenile and adult stages is a popular survival strategy for reef fish, including many surgeonfishes. Most surgeons with this strategy, however, become drab and rather uninteresting as adults. The Atlantic blue tang (Acanthurus coeruleus
) is also beautiful as an adult, and it is great for aquariums throughout all its life stages.
Blue tangs occur and are collected throughout the Caribbean, with a substantial portion of aquarium specimens coming from the Florida Keys. Because of this short supply chain, it is a rather affordable tang species in the United States. The juvenile color phase of the blue tang is bright yellow with a blue eye ring and blue fin edges on the dorsal and anal fins. It is sometimes confused with the yellow tang (Zebrasoma flavescens) from the Pacific, but the blue highlights of A. coeruleus make it easy to tell them apart. As the fish grows, the yellow transitions to a light blue-gray color, usually starting with darker bars on the body. In the subadult phase, the tail often remains yellow. Eventually, the entire body and tail transitions to the darker blue adult coloration with bright blue fin edging.
Aquarium requirements: While specimens are often available at sizes as small as 1.5 inches, this fish inevitably grows quite large. In the long run, an adult blue tang requires a swimming space of several hundred gallons, as well as an abundant habitat. For example, blue tangs at The Florida Aquarium are kept in exhibits from 3,000 gallons up to about 150,000 gallons, and individuals swim throughout all of that space. I recommend that you absolutely consider this reality before purchasing any A. coeruleus specimen. However, if you’re prepared to meet the needs of a fish this size in the long run, a tiny juvenile can begin in as little as 50 gallons, provided there is enough food to keep it busy.
Compatibility: In general, blue tangs are peaceful aquarium fish that can live in a community with almost any family of fish. They are usually reef-safe, and they are robust enough to hold their own with predators, such as triggerfishes or large angelfishes. The major compatibility challenge with this species is keeping it together with other surgeonfishes. Although it never encounters the majority of aquarium surgeonfishes in the wild, the blue tang is still quite territorial with other surgeon species. Because A. coeruleus grows large and requires a lot of territory space, it is difficult to keep it with other tangs and conspecifics. While sometimes shy in a fish community, the blue tang is a fierce combatant with other tangs and often slashes other fish with its tail scalpel. Individuals often fight to the death or fiercely enough that the loser succumbs to secondary infection. To avoid major territorial disputes, provide plenty of space for this fish and use extreme caution when combining surgeonfish species.
Feeding: In the wild, large groups of blue tangs cruise reefs and graze on algae. Feed blue tangs dried algae sheets and granules and pellet foods for herbivores. Softer pellets are excellent for this species, particularly those with high algae content. While they eat tiny bite-sized pellets, provide larger pellets that they can nibble on for longer periods of time. This extends mealtimes and provides behavioral enrichment. Feed this species as many times per day as possible to mimic the constant meals it receives in the wild.
Breeding: Blue tangs are pelagic spawners and spawn in large coordinated aggregations in the wild. This is not feasible in home aquariums, and only the largest public aquariums are likely to attempt breeding A. coeruleus.
Notes: The blue tang is susceptible to external infections, such as Cryptocaryon or Oodinium. It runs an even greater risk of acquiring unfamiliar strains of pathogens because it is so often mixed with Indo-Pacific fish, which might be harboring diseases from half a world away. For this reason, a thorough quarantine is critical for this species. Prophylactic copper therapy of 0.25 to 0.5 parts per million is safe for this fish and can help break the life cycle of parasites. Use a UV sterilizer on their display to help reduce the transmission of pathogens.
Be careful when handling this fish, as it can be defensive with its tail slash. The caudal peduncle is armed with a sharp scalpel that can easily cause a nasty wound to an unsuspecting aquarist. This scalpel also has the tendency to get snagged on nets; I recommend transferring this fish using plastic specimen cups or Tupperware containers to avoid damaging the tail or fins.
STEVE BITTER is a senior aquatic biologist at The Florida Aquarium in Tampa, Florida. His areas of interest include fish health and quarantine, scuba diving and coral reef restoration.