The Lavender Tang, Acanthurus nigrofuscus, also known as the Brown Surgeonfish, has a disk shaped body, very similar looking to other Acanthurus species. Though being the smallest and least colorful species in this genus, it is easily recognized by the dull orange spots on the head and the two dark spots at the rear base of the dorsal and anal fins. Adult coloration varies from a brown to a light grayish brown featuring a lavender color on the fins. When stressed or displaying aggression, its entire dorsal fin and upper back lighten in color, sometimes becoming noticeably yellow.
Click here to view more on Saltwaterfish.com