Orange-Band Surgeonfish

Acanthurus olivaceus

The orange-band surgeonfish (Acanthurus olivaceus), also known as the orangespot surgeonfish, is a medium-sized tang reaching about 35 cm in length. Adults are olive-grey to brown with a distinctive bright orange horizontal band or spot behind the eye that extends toward the pectoral fin, the feature that gives the species its name. The tail is lunate with pale margins. Juveniles are strikingly different, displaying a uniform bright yellow coloration with no orange marking. The transition from juvenile to adult occurs gradually as the fish matures. This species is found throughout the Pacific, from Christmas Island to Hawaii and the Marquesas, inhabiting reef flats, lagoons, and outer reef slopes. It forms large grazing schools that sweep across the reef, feeding on detritus, film algae, and diatoms from sandy and rubble substrates. Like all surgeonfish, it possesses a sharp, retractable blade at the base of the tail used for defense. The orange-band surgeonfish is one of the most abundant tangs in Hawaiian waters and a common sight for divers across its range.