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:Central Pacific
Known from various oceanic locations of the Pacific plate, ranging from the Hawaiian Islands to Palau and south to Samoa and the Marquesas Islands. Adults occur in small groups in shallow boulder regions, whilst juveniles are seen singly in rich coral habitats. Large adults have numerous fine pale-greenish lines over the head and along the body, but appear almost black at a distance, and are known as Black Surgeon in Hawaii. Small juveniles differ markedly in having bright colours and chevron-line markings. Grows large, length to 24 cm