The mouth of this species is protrusible and unfolds into a tube easily half the body length. The jaws swing forward into a long tube that strong suction to catch prey. When not in use, the entire apparatus is conveniently folded under the head. Small juveniles are brown with thin white bars and closely resemble a species of Wetmorella. Color varies with age and sex, but adult color varies additional, including with an all-yellow xanthic form. Sub adults and females are brown or, not uncommonly, uniformly yellow. Terminal males are dark with a white head and a dark streak extending horizontally through the eye. Male becomes ornamented with orange and yellow over the back. Juveniles dark with fine vertical white lines. Intermediates with yellow blotches, pale tail and sometimes with black pectoral fins (Ref. 48636).