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Blue Tang, Acanthurus coeruleus


The blue tang, blue barber or Acanthurus coeruleus, can be confused with the royal surgeon fish (Paracanthurus Hepatus), because in the areas of origin the royal surgeon fish is called Blue tang or Caribbean Blue tang, which generates some confusion.Although the two fish are Acanturids, they are two different varieties.The first description of this fish is the work of Block & Schneider in 1801, and its name Acanthurus coeruleus refers to its spiny tail (Acanthurus) and its dark blue color like the sky (coereleus).


The blue tang is morphologically very interesting. Like all surgeons, he has a flattened, slightly oval body and a small mouth with serrated teeth.It has two removable spines located on one side and the other of the caudal peduncle, which they use to defend themselves against other fish and that can be dangerous when handled.Its color changes as it matures, even as an adult it can change color if it feels threatened.When the Acanthurus coereleus is young, its coloration is intense yellow with light blue lines that mark the perimeter of the dorsal fin and the anal fin, as well as a very characteristic blue spot on the eye.As it grows, it changes and takes its color to blue. It will first turn light blue and its tail fin will remain yellow.

When they have reached their adult age, they are completely blue or blue to violet, and a spot on the caudal fin that can be white.Adult specimens can change the tone of their skin, which under certain circumstances can change to a greyish-blue or orange-brown color, with more accentuated markings in strong blue, black or brown.In the aquarium they do not measure more than 7,8 inch, but in nature their size is much larger, around 29,53 inch.

Distribution and habitat

It is a marine fish with a wide geographical distribution. It can be found in the western Atlantic Ocean, Bermuda, the Caribbean, South America, and Africa. Its natural habitat is coral reefs and rocky coastal areas, where it forms small groups.

Aquarium Conditions

The aquarium must be of a good size with at least 210 gallons, they are tireless swimmers and need space, if we keep them in small aquariums, their aggressiveness increases.The water temperature should be around 71,6ºF to 78,8ºF, with a pH between 8.1 and 8.4, the salinity of the water should be around 1.023-1.25. Ideally, the parameters should remain stable.For decoration, we must try to reproduce their natural habitat with rocks and corals, in which we will leave spaces for them to hide and sleep. At the top, the areas should be open for them to swim freely. A good idea is to provide a current of water, so that the fish can swim against the current. For good aquarium maintenance, 10% of the aquarium water should be changed every two weeks. In general they are tough but on some occasions they are sensitive to bacterial diseases that you can generally treat with amoxicillin for fish or ampicillin for fish.


The blue tang is herbivorous, in its natural state they eat benthic algae, in the aquarium they are usually fed with all kinds of food in which vegetables and algae are present. There are preparations based on dried algae, which are ideal for the diet of these fish, which can be supplemented with frozen artemia, mysis… A good idea that some aquarists use is to add broccoli, zucchini, lettuce or spinach leaves, which are left to float in the water, and serve as a complement to their diet. Others let algae grow in their aquariums, which serve as free food for their surgeon fish.

Behavior and Compatibility

The Acanthurus coereleus is not very sociable and it is better to have only one in the aquarium, even with others of the same species it does not get along well, and is usually aggressive. However, if the aquarium is the right size, it can live with other species that are calm, as long as the blue tang is the last to arrive at the aquarium. Congeny with gobies or angel fish, species that are found in their same habitats.


Despite the efforts that have been made, it is currently not possible to reproduce the blue tang in captivity, not even in companies specialized in breeding fish for aquariums, they have managed to be successful. The difficulty begins when the eggs hatch. The stage in which Acanthurus coeruleus are fingerlings is very long, going through previous seasons as pelagic larva and planktonic larva, in which they are very fragile and easy to damage. Remember that in the aquarium we will probably only have one specimen, or in the best of cases if we want to try to reproduce we will have a couple, which requires a good installation. In nature, surgeon fish congregate in groups of six to seven thousand individuals for spawning, although there are also couples far from the group. Courtship begins with the male being somewhat aggressive towards the female, so that she spawns with them.

Once the female accepts, the two swim to the surface in the late afternoon, releasing the eggs on the surface and the male’s sperm. The eggs are very small, with a diameter of 0.8 millimeters and they float, because they contain a small drop of oil. Within 24 hours, the eggs hatch into a small transparent diamond-shaped larva, thin and flat, with a triangular head and silvery belly. In the early stages it feeds on plankton. Until it reaches a size of 2 to 6 millimeters, it does not develop dorsal and anal fins and is covered with scales. When they reach 13 millimeters, they develop the caudal spine that serves as protection. Their sexual maturity is reached when they are between 9 and 12 months old and about 3,9 inch long.


Acanthurus coeruleus fish are difficult to acclimatize to the aquarium, but once this phase is over, they are quite resistant. For them to be in perfect health, it is necessary that they have an aquarium partner (not of the same species) and that the quality of the water is good and stable. They are prone to skin diseases, they are called dry skin fish. If we see that our fish lose color, it is because the diet is not being adequate, it lacks vitamins or the aquarium does not meet the conditions that the fish needs. It is a fish that is usually available in pet stores throughout the year, although the price of Acanthurus coeruleus will depend on the size of the specimen. Antibioticsfish