Habitat: Marine. Reef-associated, rocky areas. Depth range 2 - 25 m. Natural History Notes: Non territorial herbivore specialized for grazing on filamentous algae. May be frequently seen moving with Acanthurus bahianus along in a single group, scraping algae constantly. Often ingests sand with algal food. There is probably some grinding of the algae in the stomach. Characteristics: Overall brown with about ten narrow darker brown bars, most of which are posterior to pectoral fin, usually visible on the sides. Can pale or darken dramatically. Dark sheath of caudal spine, dark area extending from base of pectoral fin outward along leading edge.