Yellow tangs have a clear larval stage before developing into juveniles. Juveniles and adults have a narrow, oval body. They have an average length-weight ratio between 2.93 and 3.16. They have a long snout for eating algae, a large dorsal fin with four to five spines, and an anal fin with three spines. Like other surgeonfish and tangs (Acanthuridae), yellow tangs have a white, scalpel-like spine on both sides of the tail that can be used for defense or aggression. Yellow tangs are named for their bright yellow coloring; the only area that is not yellow is the white spine. At night, this bright yellow color changes to a darker, grayer yellow with a white lateral line.
Range length: 20 (high) cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike