The common name "surgeonfish" is derived from a characteristic that clearly distinguishes Acanthuridae from other fish families: the spines or "scalpels" on the caudal peduncle, one or more on each side. Based primarily on differences in this characteristic, the family can be divided into three subfamilies: The Acanthurinae, in which the peduncular spine rests in a groove and can be erected in defence during the fights, the Nasinae and Prionurinae in which the peduncular feature is arranged as one or more fixed blades on each side, that are sharp and elongate with age.
Place of origin:Western Indian Ocean
Widespread Indian Ocean, ranging to Bali where it mixes with Acanthurus olivaceus. Occurs in small groups on reef flats and slopes. Identified by the bluish black colour, peduncular spine surrounded by black with blue edge, and a black mark above pectoral fin base that develops into short, double stripes. Juveniles black to yellow body, yellow caudal fin and dark eye. Length to 31cm