Indo-Pacific: Red Sea and East Africa to the Line, Marquesan, and Tuamoto islands, north to the Ryukyu and Bonin islands, south to New Caledonia and Tonga; throughout Micronesia. Excluding the Hawaiian Islands.

Adults generally brown; dorsal part of head and nape darker, grading to tan on lower part of head and breast. The scales have darker brown margins. The lips are whitish lips; the suborbital is mostly blue; the preopercle and opercle scales with blue centers. The median and pelvic fins are brown; the pectorals are dusky; a well-defined dark brown or blackish spot is sometimes present at base of posteriormost dorsal rays, which distinguishes it from S. lividus where the spot is diffuse. Males in courtship or guarding eggs with broad white bar across middle of body and pale blue stripe from mouth to upper part of pectoral fin.

Inhabit reef flats and lagoon reefs. Frequently occur in colonies associated with live or dead branching staghorn coral (Acropora). Feed on algae, gastropods, sponges, and copepods. Territorial, maintain and 'weed' filamentous algae patches growing on dead coral.

They attack human intruders without hesitation, sometimes taking painful nips. Particularly aggressive during reproductive periods. The species emit clicking noises during aggressive encounters.