Pale in front, dark behind, with thick white lips; the sand-sifting thicklip of muck slopes.
A large wrasse commonly seen at 30 to 50 cm, with thick pale fleshy lips, a green-marked head carrying fine pink lines around the eye, a pale grey to whitish front half and an abruptly darker brown to blackish rear half, and a yellow-green tail. Published maximum lengths run considerably higher than 50 cm, but fish above that are unusual on a dive. Juveniles look like a different animal and are worth logging as such by anyone who has not seen both: sharply white in front, black behind, with a yellow tail base, and they hang around rubble and coral heads in the shallows.
The species to separate it from is the barred thicklip wrasse Hemigymnus fasciatus, which has the same lips and head lines but is crossed by five pale vertical bars at every stage rather than divided into two blocks of colour. Adult melapterus darkens overall with age and the boundary between the two tones becomes less clean, so on a large old fish the absence of bars is the more reliable character.
It feeds by scooping sand and fine rubble into the mouth, sorting out worms, small crustaceans and molluscs and expelling the sediment, and it turns small rubble pieces with its lips. That method works on bare sediment as well as on reef, and it is why this is the thicklip that stays common on the muck slopes of Lembeh Strait and Dauin while the barred species thins out. It ranges widely over a dive site and rarely holds still, so it is usually photographed as it passes rather than approached. Recorded from the shallows to about 30 m.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.