Diet

• Primarily herbivorous, feeding on benthic microalgae, filamentous algae, diatoms, fleshy macroalgae, and detritus scraped from the substrate.

• It may also consume hydroids and small pieces of animal material while foraging.

• Often feeds singly or in small groups, although larger aggregations can occur.

Range

• Widely distributed through the tropical Indo-Pacific.

• In the eastern Pacific, it ranges from the southern Gulf of California and Baja California Sur south to Ecuador.

• It occurs along the Mexican Pacific coast, including Guerrero and the Zihuatanejo region.

Habitat

• Occurs on reef habitats, sandy slopes, and in protected bays and lagoons.

• Juveniles favour shallow, protected and often turbid inshore waters, while adults generally occupy deeper protected bays, lagoons, and outer reef areas.

• Recorded from approximately 1–100 metres.

Description

• Large, deep-bodied surgeonfish with an elongate oval, laterally compressed body and a steep head profile.

• Adults can reach about 70 cm in total length.

• Body is generally purplish-grey to brown, with a broad dull-yellow area extending across the snout and around the eye.

• The outer portion of the pectoral fin is yellow, while the dorsal and anal fins have yellowish-grey to dull-yellow coloration.

• The base of the caudal fin is often marked by a conspicuous white band, contrasting with the purplish caudal fin.

• A large, retractable spine on each side of the caudal peduncle is characteristic of surgeonfishes and provides an effective defensive weapon.