The doubleband surgeonfish or lieutenant tang (Acanthurus tennenti),[2] is a marine ray-finned fish in the family Acanthuridae.

The colour is variable, the sexes being similar except in the breeding season, when the mature male takes on a distinctive appearance.

This fish is usually orange-beige, olive-tan or steely grey, but can turn a dark brown shade flushed with red or purple when stressed.

There are two dark streaks behind the eye, and the scalpel-like scales that project from the caudal peduncle are blackish and surrounded by a large black spot with a bluish border.

[3] This species has a wide distribution across the tropical and subtropical Indo-Pacific region; its range extends from East Africa and Madagascar to southern India, Sri Lanka, Malaysia, Thailand and Indonesia.