Naso lituratus is a species of fish in the family Acanthuridae, the tangs and unicornfishes. Its common names include barcheek unicornfish, naso tang, and orange-spine unicornfish. Unique to members of Acanthuridae, including Naso lituratus, are the Epulopiscium bacteria. These bacteria influence the digestion of Naso lituratus, helping them process the algae in their diet. Naso lituratus can be found in the Indian Ocean and the Pacific Ocean. This species can be easily recognised by two bright orange forward-hooked spines on the caudal peduncle (the tail base), its orange lips and black face mask. The body is brownish grey with yellow nape and there is a broad black band on the dorsal fin. It reaches about 45 cm in length.