The Atlantic blue tang (Acanthurus coeruleus) is a surgeonfish found in the Atlantic Ocean and the Caribbean Sea. It is often seen schooling around reefs by divers and snorkelers, and Sosua Beach is no exception. Some people also call it Yellow Barber and Doctor fish ( Dominicans call it pez doctor ).
It is relatively easy to spot surgeonfish, but don`t confuse the Caribbean species with Hollywood-famous Pacific Tang ( Dory in finding Nemo ). The Atlantic Blue Tang are deep bodied and oval with caudal spine on each side, without the black margins as Dory. ( some Caribbean ones will show the yellow tail color too). Their mouth slightly protrudes, which helps feeding between rocks.
Habitat & Range:
The Atlantic Blue Tang is found in the Caribbean Sea, specially around the shallow reefs in the Dominican Republic. They are also found in the Bahamas, Florida, Belize, Bonaire, Brazil and the Gulf of Mexico. They are active during the day, usually swimming around reefs and hiding in crevices at night.
Juveniles stay in cover most of the time until reaching larger size. Clear shallow water and sunlight are important to this species because those conditions are needed for lots of algae growth on the coral and rocks.
Throughout its life, it moves through various color phases, Juveniles are bright yellow color, with blue bordered fins. Then it turns into a pastel blue with hints of yellow in the tail fin (2-3 inch in size). As it becomes an adult, it turns into a blue accented color with a white or yellow caudal spine ( now the fish is around 5 inches ).
Acanthurus coeruleus are herbivores, that feed primarily on benthic algae including the green, red, brown and blue-green algae; sometimes also on seagrass. They are herbivores that feed primarily on benthic algae including brown algae, red algae, green algae, and blue-green algae, and occasionally on seagrass. They feed during the daylight hours and wedge themselves between crevices and caves at night to avoid predation.
Size & Breeding
This fish reaches a size of 25cm(9 inches) but can grow up to 39cm (15 inches). Their lifespan is about 30-45 years in the wild, less in captivity. They generally mate in large aggregations, of over a hundred individuals over sandy patches between reefs. They spawn on depths of 6-1o meters with strong currents to sweep the fertilized eggs to sea. Their eggs take 24 hrs to hatch, and the pelagic larvae are less than 2mm in length.
Atlantic blue tangs are called doctors because they engage in cleaning behaviors, removing ectoparasites and damaged tissue form the surface of other fish. Fish improve health when these unwanted organism are removed from their skin.