Distinctive Characters: Dorsal fin with 9 spines and 10 rays. Anal fin with 3 spines and 8 rays. Pectrol fin with 12 rays. Body depth 2.3-2.7 in standard length. Body moderately deep. Dorsal profile of head straight to eye, then becoming convex. Adults develop a large, fleshy hump on forehead. Lateral line interrupted below posterior portion of dorsal fin base. Caudal fin rounded.
Colour: Body olive to blue-green with vertical dark lines on scales. Irregular lines on head and two black lines extending back from eye. Juveniles pale greenish with elongate dark spots on scales of body tending to form bars; two black lines posteriorly from eye.
Habitat and Biology: Found mostly on deeper portions of coral reefs to depths of 60 m. Solitary. Feeds mainly on hard shelled prey including molluscs, crustaceans and sea urchins.
Remarks: Cheilinus undulatus is the largest of the family Labridae. In spite of its large size, it is a wary fish. This species is protected in the Maldives.