Body robust, the depth contained 2.4 to 3.4 times in standard length (for fish 12 to 179 cm standard length), the body width contained 1.5 to 1.75 times in the depth. Head length contained 2.2 to 2.7 times in standard length; interorbital width contained 3.3 (for fish 177 cm standard length) to 6.2 (for fish 12 cm standard length) times in head length; interorbital area flat to slightly convex, the dorsal head profile convex; preopercle subangular, finely serrate, the corner rounded; upper edge of operculum convex; eye diameter contained 5.8 to 14 times in head length; nostrils subequal; maxilla reaching past vertical at rear edge of eye; midlateral part of lower jaw with 2 or 3 rows of teeth (specimens of 20 to 25 cm standard length) increasing to 15 to 16 rows in a fish of 177 cm standard length; canine teeth at front of jaws small or absent. Gill rakers of juveniles 8 to 10 on upper limb, 14 to 17 on lower limb; rudiments in adults are difficult to distinguish from the bony platelets covering the gill arch. Dorsal fin with XI spines and 14 to 16 rays, the 3rd to 11 th spines subequal, their length contained 3.1 to 5.7 in head length and much shorter than longest rays in adults; anal fin with III spines and 8 rays; pectoral-fin rays 18 to 20; pectoral-fin length contained 1.8 to 2.2 times in head length; pelvic fins not reaching anus, their length contained 2.1 to 2.6 times in head length: caudal fin rounded. Lateral-body scales smooth, with auxiliary scales; lateral-line scales 54 to 62, the anterior scales with branched tubules (except small juveniles); lateral-scale series 95 to 105.
Colour: Small juveniles (12 cm standard length) yellow, with irregular broad black bars on body, the first from spinous dorsal fin to belly and chest and extending onto head, the second from base of soft dorsal fin to anal fin and the last at base of caudal fin; small adults (20 to 50 cm standard length) with irregular white or yellow spots on the black areas and fins with irregular black spots; adults (80 to 150 cm standard length) dark brown with faint mottling, the fins with numerous small black spots: large adults (160 to 230 cm standard length) dark brown, the fins darker.

E. lanceolatus is the most widely distributed grouper in the world; it occurs throughout the Indo-Pacific region from the Red Sea to Algoa Bay, South Africa and eastward to the Hawaiian and Pitcairn Islands. In the western Pacific, E. lanceolatus ranges northward to southern Japan and southward to Australia (from northern Western Australia to northern New South Wales, and Kailola and Jones (1981) reported a 212 cm total length specimen from South Australia). It is known from oceanic islands as well as continental localities. Its absence in the Persian Gulf is puzzling

E. lanceolatus has been caught at depths of 100 m, but it is more often found in shallow water. Specimens more than a metre long have been caught from shore and in harbours. It is commonly seen in caves on coral reefs and around wrecks; and adults as well as juveniles are found in estuaries. A favourite food on coral reefs and in rocky areas is spiny lobsters. A 177 cm standard length fish, caught from shore at Maui, Hawaiian Islands, contained 2 spiny lobsters and several large crabs. It is also known to eat a variety of fishes, including small sharks and batoids and juvenile sea turtles; in South African estuaries, the main prey item is the mud crab (Scylla serrata).

E. lanceolatus is one of the two largest species of groupers in the world (the other is E. itajara of the Atlantic and eastern Pacific oceans). Schultz (1966) reported a 231 cm total length, 214 kg specimen from Bikini Atoll. Grant (1982) mentioned a specimen of 288 kg from Queensland. According to Fourmanoir and Laboute (1976), E. lanceolatus can attain 400 kg.

E. lanceolatus and E. itajara were often assigned to the genus Promicrops Poey; but C.L. Smith (1971) demoted Promicrops to a subgenus of Epinephelus, and Heemstra and Randall (1993) agree with this action. These two species are closely related; both grow to enormous size and have a similar body shape, small eye, wide interorbital area, numerous platelets on the gill arches, short dorsal-fin spines, similar fin counts, and anterior lateral-line scales with branched tubules. E. itajara differs from E. lanceolatus in having ctenoid scales on the sides of the body, and small black spots on the head and dorsal part of the body.