Grey Sweetlips

Diagramma labiosum has fleshy lips that become more swollen as the fish matures. The chin has six pores on it but there is no median pit. The dorsal fin contains 9-10 spines and 22-25 soft rays while the anal fin contains 3 spines and 7 soft rays. It is slate-grey in colour, the adults and subadults being unmarked unlike the spotted, parapatric painted sweetlips (D. pictum). The juveniles are dark brown to black dorsally, split into 3 or more wide horizontal stripes by narrower whitish-blue stripes; they silvery yellow ventrally. The dorsal and caudal fins are yellow with black blotches and discontinuous stripes which grow with age and fragment into small circular spots before fading away in adults. As the fish matures from a juvenile to an adult the caudal fin form changes from being rounded to truncate. This species attains a maximum recorded total length of 90 cm (35 in) and a maximum published weight of 6.3 kg (14 lb).

Diagramma labiosum is found in the eastern Indian Ocean and southwestern Pacific Ocean. Its range encompasses southern New Guinea and northern Australia. In Australia its range extends from the Houtman Abrolhos Islands in Western Australia to Sydney, including Lord Howe Island in the Tasman Sea.