Sea Fish

Blue Surgeonfish, Acanthurus coeruleus

  • Scientific name: Acanthurus coeruleus
  • Common name: Blue surgeonfish, blue barber
  • Aquarium size: 800 liters
  • Temperament: Aggressive towards other Acanthurus
  • Temperature:  Between 22º and 26º
  • pH: Between 8.1 and 8.4
  • Diet: Hervivore
  • Length: 20 centimeters



The blue surgeonfish, blue barber or Acanthurus coeruleus , can be confused with the royal surgeonfish (Paracanthurus Hepatus), because in the areas of origin the royal surgeonfish is called Blue tang or Caribbean Blue tang, which generates some confusion.
Although the two fish are Acanturidae , 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 surgeonfish is morphologically very interesting. Like all surgeons, it 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 from other fish and which 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, which 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 adulthood, they are completely blue or blue to violet, and a spot on the tail fin that can be white.
Adult specimens can change the tone of their skin, which under certain circumstances can become a grayish-blue or orange-brown color, with more accentuated markings in strong blue, black or brown.
In the aquarium they do not reach more than 20 centimeters, but in nature their size is much larger, around 75 centimeters.

Distribution and habitat

It is a marine fish with a great geographical distribution. It can be found in the western Altlantic 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 800 liters , they are tireless swimmers and need space, if we keep them in small aquariums, their aggressiveness increases.
The water temperature should be around 22º to 26ºC, 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 stream of water, so the fish can swim against the current.
For good aquarium maintenance, 10% of the aquarium water should be changed every two weeks.

Ideas for setting up your aquarium

  • Best complete aquariums
  • Best Small Aquarium
  • Best external filters for aquarium
  • Best aquarium heater
  • Best Aquarium Oxygenator
  • Best Aquarium LED Display
  • Better sand
  • Best substrate for aquarium
  • Best compost for plants
  • Best Aquarium Stones
  • Best aquarium logs
  • Best Aquarius Test
  • Best Ph meter 
  • Best fish food
  • Best Fish Food Dispenser


The blue surgeonfish is herbivorous, in a natural state they eat benthic algae, in the aquarium they are usually fed with all kinds of foods 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 complemented with frozen foods of brine shrimp, mysis …
A good idea and used by some aquarists is to add broccoli, zucchini, lettuce or spinach leaves , which are allowed to float in the water, and which serve as a complement to your day.
Others let algae grow in their aquariums, which serve as free food for their surgeonfish.

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 on well, and it 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 surgeonfish is the last to arrive at the aquarium.
Congenies with gobies or angelfish, species found in the same habitats.


Despite the efforts that have been made, at present it is not possible to reproduce the blue surgeonfish in captivity, not even in companies specialized in the breeding of aquarium fish, they have managed to be successful.
The difficulty begins when the eggs hatch. The stage in which the Acanthurus coeruleus are fry is very long, going through previous seasons such as pelagic larvae and planktonic larvae, in which they are very fragile and easy to damage.
Remember that in the aquarium we will surely 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,they congregate in groups of six to seven thousand individuals for spawning, although there are also pairs 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 towards the end of the afternoon, releasing the eggs on the surface and the male’s sperm.
The eggs are very small, they have a diameter of 0.8 millimeters and they float, because they contain a small drop of oil. Within 24 hours, the eggs hatch and a small, thin, flat, transparent diamond-shaped larva is hatched with a triangular head and silver belly.
In the first stages it feeds on plankton.Until it reaches a size of 2 to 6 millimeters, it does not develop the dorsal and anal fins and becomes 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 10 centimeters long.


Acanthurus coeruleus fish are difficult to acclimate to the aquarium, but after this stage, they are quite resistant.
In order for them to be in perfect health, it is necessary that they have an aquarium companion (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 that 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.

Surgeonfish photos

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