Naso lituratus

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.
The "Naso lituratus" species 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.
It can be found on coral reefs, often in pairs.