Body depth contained 3.0 to 3.6 times in standard length (48 specimens 10 to 43 cm standard length). Head length contained 2.3 to 2.6 times in standard length; interorbital area flat or slightly concave, the dorsal head profile of adults with a ventral bend at orbits; preopercle rounded, with minute serrae mostly covered by skin and a shallow indentation just above the “corner”; upper edge of operculum straight or slightly convex; posterior nostrils usually distinctly larger than anteriors; maxilla reaches to or past vertical at rear edge of orbit, the ventral edge smoothly curved at distal expansion; lower jaw strongly projecting, the midlateral part with 2 to 4 rows of teeth. Gill rakers 7 to 9 on upper limb, 14 to 17 on lower limb, 21 to 26 total. Dorsal fin with XI spines and 15 to 17 rays, the third or fourth spine longest, its length contained 2.3 to 3.4 times in head length and shorter than longest dorsal-fin rays, the interspinous membranes moderately incised; anal fin with III spines and 8 rays, the second and third spines subequal, their length contained 2.8 to 4.2 times in head length; pectoral-fin rays 17 to 20; pectoral-fin length contained 1.5 to 2.0 times in head length; pelvic-fin length 1.8 to 2.5 times in head length; caudal-peduncle depth contained 3.2 to 3.7 times in head length; caudal fin rounded; length of middle caudal-fin rays contained 1.5 to 2.0 times in head length. Lateral-body scales smooth, except for area covered by pectoral fins; lateral-line scales 48 to 52; lateral-scale series 86 to 103. Pyloric caeca 25 to 27.
Colour: Pacific Ocean specimens: Head and body pale greyish brown with dark brown spots (centre of spots darker than the diffuse edges) that are large and well-separated in young, becoming relatively smaller, more numerous and closer together in adults; median and pelvic fins with similar dark spots; pectoral fins usually dusky, with white line along the edge and usually a few faint dark spots; some specimens with a faint oblique dark line across lower part of chest; median fins with narrow pale margin posteriorly; no dark spots on underside of lower jaw.
Indian Ocean specimens: Head and body with round to polygonal brown to dark brown spots, variable in size (some spots on juveniles may be as large as eye) and close-set, the narrow interspaces forming a pale network pattern; median fins yellowish, with blackish brown spots like those on body; soft dorsal, caudal, and anal fins with pale margin; underside of lower jaw usually with dark spots. Small juveniles (5 to 7 cm standard length) with dark spots on head and body fewer and much larger than in adults, those on caudal fin represented by a broad black area covering two-thirds of the fin; Pacific Ocean juveniles with prominent white blotches as shown in figure.

Indo-Pacific region from east coast of Africa (Kenya to Natal, South Africa) to the central Pacific, including Madagascar, Comoros, Mascarenes, Seychelles, Chagos, Nicobars, Cocos-Keeling, Western Australia (Scott Reef), Indonesia, Okinawa, Great Barrier Reef, Marquesas Islands, and most western Pacific islands (both on and off the Pacific Plate). E. macrospilos is not known from the Red Sea, Persian Gulf, or Hawaii.

Coral reefs to depths of at least 44 m. Feeds on crustaceans (mainly crabs), fishes, octopuses, and squids.

Attains at least 43 cm standard length and 2.0 kg.

Specimens from the western Indian Ocean differ from those in the eastern Indian and Pacific oceans in usually having dark spots on the underside of the jaw, and the dark spots on the head and body are larger and close-set, forming a pale mesh dorsally on fresh specimens. But Heemstra and Randall (1993) were unable to find any other differences between specimens of these two populations. Burgess and Axelrod (1974) illustrated the colour pattern of juveniles (figs 230 to 232, photographs by Shih-chieh Shen of specimens 6 to 9 cm standard length from Taiwan labelled “Epinephelus tauvina”). E. macrospilos was illustrated as “Epinephelus quoyanus” by Masuda and Allen (1987:116; and the same specimen was illustrated by Katayama, 1988:pl. 115, fig. E, as E. faveatus) and Gloerfelt-Tarp and Kailola (1984:134). E. macrospilos seems to be replaced along the coast of India and Sri Lanka by the closely related E. faveatus; and along the northern coast of Australia, it seems to be excluded by E. quoyanus. Both E. macrospilos and E. quoyanus occur at the Riu Kiu Islands, Taiwan, Moluccas and probably at other localities in Indonesia. E. macrospilos is compared with E. bilobatus, E. corallicola, E. faveatus, E. hexagonatus, and E. howlandi in the Taxon description, Interchangeable taxa sections of these species. Western Indian Ocean specimens of E. macrospilos are often confused with the other “reticulated groupers” (E. bilobatus, E. faveatus, E. hexagonatus, E. maculatus, E. melanostigma, E. merra, E. quoyanus, and E. spilotoceps).

E. maculatus has the dorsal-fin membranes not incised between the spines; lateral-body scales ctenoid, lateral-scale series 102 to 120; juveniles are yellowish brown, with irregular white spots and blotches on head, body, and dorsal fin and a few small black spots on head and fins.

E. melanostigma has the lateral-body scales ctenoid, lateral-line scales 56 to 68, and a large black blotch (which extends halfway to dorsal-fin margin) on body at base of last 4 dorsal-fin spines.

E. merra has the lateral-body scales ctenoid, and pectoral fins covered with distinct small black spots mainly confined to the rays.

E. quoyanus has larger pectoral fins (their length contained 1.2 to 1.7 times in head length), lateral-body scales distinctly ctenoid, chest with 2 oblique dark brown bands (or large blotches linked by narrow bands), pectoral fins with semicircular reddish brown blotch covering most of the base, and small juveniles are coloured essentially like the adults.

E. spilotoceps has the lateral-body scales ctenoid, lateral-line scales 59 to 69, black spots on snout about size of nostrils, and caudal-peduncle depth contained 3.7 to 4.3 times in head length.