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Acanthurus coeruleus is known under numerous common names in English, including Atlantic blue tang, Blue tang, Blur tang, Blue tang surgeonfish, Blue doctor, Blue doctorfish, Yellow doctorfish, Blue barber, and Yellow barber.

Acanthurus coeruleus has not been evaluated for the IUCN Red List of Threatened Species.

In addition to being a popular aquarium fish, this species is also marketed fresh as food.

Geographical range, habitat and habits

The Atlantic blue tang is found in the Eastern and Western Atlantic. In the Western Atlantic, it can be encountered from New York in the United States down to Brazil, including Bermuda and the Gulf of Mexico. In the Eastern Atlantic it has been observed in the waters of Ascension Island. The geographical range for the Atlantic blue tang is 42°N to 11°S, and 100°w to 4°w.

The Atlantic blue tang inhabits coral reefs and inshore grassy or rocky areas at depths of 2-40 meters / 6-131 feet. Atlantic blue tangs that live among corals will use holes and crevices to hide themselves from predatory species. Juveniles spend so much time hiding that they are rarely seen on the reef.

This is chiefly a day active species that stays hidden during the night. It lives singly, in pairs, or form small groups consisting of up to a dozen specimens. Occasional observations of large foraging aggregations exist from shallow reef environments. Such aggregations don’t have to be comprised of Atlantic blue tangs only; they can also include other species of surgeonfish, e.g. Acanthurus chirurgus.

Juvenile fish is known to set up cleaning stations, sometimes together with Acanthurus chirurgus and Abudefduf saxatilis. At such cleaning stations, they have been observed removing  parasites and molted skin from the turtle Chelonia mydas.

Size and appearance

The largest scientifically measured Atlantic blue tang was 39.0 cm /15.4 in.

This is a deep-bodied fish with a characteristic yellow caudal spine and a very distinct colouration. The snout is pointy, the mouth is small, and the eye is situated high on the head.
The fish is covered in small scales. Spines used for protection and to establish dominance are located on both sides of the caudal peduncle (one spine per side). When the spine is not being used, the fish will keep it hidden inside a horizontal groove.

Juveniles are bright yellow, but will change into a combination of yellow of blue during adolescence. The young fish can for instance sport a yellow body with blue fins, or develop blue spotting.  In some specimens, you can see blue crescents over and under the pupils of the eye. This species then goes through an intermediate phase when it is blue with a yellow tail. The blue colour will darken into bright blue or purplish-gray. The adult fish is deep blue or purplish with a yellow caudal spine.

Atlantic Blue Tang care

It is not advisable to house this species in an aquarium smaller than 50 gallons / 190 litres.
Decorate the aquarium in a fashion that makes it possible for the Atlantic blue tang to carry out its natural scraping and sorting behaviour. Housing Atlantic blue tang together with similar species is generally not recommended, since it can lead to violence. Groupers and lionfishes can also become a problem.

Keep the water temperature around 77-82 degrees F / 25-28 degrees C. The pH-should be in the 8.0-8.4 range. It is important to keep the environment as stable as possible, because this fish doesn’t handle change very well. The levels of ammonia and nitrite must be non detectable and the amount of nitrate should never be allowed to exceed 25 ppm. Powerful water movements and a high level of oxygen is strongly recommended.

Feeding Atlantic Blue Tang

In the wild, this species feeds chiefly on algae which it grazes from rocks and corals. Unlike many other species of surgeonfish, the Atlantic blue tang can not handle ingested sand or other calcareous materials very well.

Feed your Atlantic blue tang many small servings throughout the day instead of just one or two large meals. Natural algae growth should be encouraged in the aquarium, since this will provide the fish with a constant source of food and allow it to carry outs its natural grazing behaviour. Naturally occurring algae is rarely enough and it is therefore a good idea to supplement with fresh algae, dried algae and algae based foods, e.g. spirulina flakes.

Breeding Atlantic Blue Tang

The Atlantic blue tang will become sexually mature when it is 9-12 months old and 11-13 cm / 4-5 in long.

In the wild, spawning takes place during late afternoon or in the evening. Prior to spawning, the fish will change colour; instead of its common uniform dark blue colouration it will be pale blue on the anterior part of the body and dark blue posteriorly. The males court the female members of the school aggressively before any actual spawning takes place.  

During spawning, the fish swims rapidly towards the surface while releasing eggs and sperm. The eggs are not very big (normally less than 1 mm in diameter) and contain oil which makes them buoyant. The eggs float around in the water for roughly 24 hours before hatching. The larvae are small and transparent, with silvery bellies. When the offspring has reached a size of 2-6 mm they will start developing dorsal fins, anal fins and scales. The caudal spine will appear when the fry is about 13 mm in length.

When the fry is big enough it will drift inshore where it will metamorphose into a juvenile fish. The silvery colour will vanish and the fish will instead become brown. After completing its metamorphose (this will normally take about a week) the fish will settle on the bottom inshore.

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Mimic Surgeonfish – Acanthurus pyroferus
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Orangeshoulder Surgeonfish – Acanthurus olivaceus
Powder Blue Tang – Acanthurus leucosternon
Powder Brown Tang – Acanthurus japonica
Purple Tang – Zebrasoma xanthurum
Sailfin Tang – Zebrasoma veliferum
Scopas Tang – Zebrasoma scopas
Whitecheek Surgeonfish – Acanthurus nigricans
Yellow Tang – Zebrasoma flavescens