Pseudanthias olivaceus is a species of reef fish that belongs to the genus Pseudanthias, which includes about 60 other species of anthias. It has an olive body with a yellow tail, and a yellow and blue stripe from eye to pectoral fin. Males have orange blotches on their sides, a dark red blotch on their pectoral fin, and orange bands on their tail lobes. It grows up to 12 cm in length . It is found in the central Pacific Ocean around Cook Island, Austral and Society Islands, Line Island and Tuamotu Archipelago. It feeds on zooplankton and lives in harems.