About Acanthurus bahianus Castelnau, 1855
Acanthurus bahianus, commonly called ocean surgeon, has oval-shaped bodies with uniform coloration, most often blue-gray to dark brown. They have pale to dark markings surrounding their eyes, and patches of light yellow are present on their bodies. Most individuals have blue or white markings on their dorsal, anal, and tail fins, and pale bands may sometimes be visible at the base of the tail. They commonly swim in mixed-species schools that include the Atlantic blue tang surgeonfish. The maximum recorded length of this species is 38 cm (15 in). Their dorsal fins have a total of 9 spines and between 23 and 26 soft rays. Their anal fins have 3 spines and between 21 and 23 soft rays. Their caudal fins are roughly emarginate, and both the body and head of this surgeonfish are deep and compressed. Acanthurus bahianus inhabits coral reefs and feeds on algae. It occurs in the central and southern Atlantic Ocean, along the coast of Brazil from the state of Maranhão south to the state of Santa Catarina. Its range also includes multiple islands: Fernando de Noronha, Atol das Rocas, Trindade, Ascension Island, and St. Helena.
