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.
- Care Sheets
Place of origin:Western Pacific
Northern West Pacific, southern Japan, Philippines and Bonin, Indonesia. Occurs on outer reef crests and slopes to about 20m depth. Usually occurs in small to large aggregations. Very similar to Acanthurus nigricans in behaviour and looks A.Japonicus is best distinguished from A.nigricans by the large white area below the eye and the lack of the yellow sub-marginal band in the caudal fin. The two species co-occur in southern Japan and Bonin Islands. Length to 14cm.