Body depth greater than or subequal to head length, depth contained 2.3 to 2.8 times in standard length (for fish 9 to 41 cm standard length). Head length contained 2.5 to 2.7 times in standard length; dorsal head profile of adults straight to concave, the nape distinctly convex; interorbital area flat to slightly convex; preopercle rounded, finely serrate, with a shallow notch just above the “corner,” the lower edge serrate or irregular with broad spinules, usually exposed; subopercle and interopercle finely serrate; maxilla reaches past eye. Gill rakers 7 to 9 on upper limb, 14 to 16 on lower limb. Dorsal fin with IX spines and 14 to 16 rays, the membranes distinctly indented between the spines; anal fin with III spines and 9 rays; pectoral fins with 18 to 20 rays; pectoral fins subequal to pelvic fins, pectoral-fin length contained 1.5 to 1.7 times in head length for fish 9 to 30 cm standard length (in fish larger than 30 cm standard length, the pelvic fins are longer than the pectoral fins); pelvic fins reaching or extending beyond anus; caudal fin rounded. Lateral-body scales ctenoid; lateral-line scales 66 to 80; lateral-scale series 115 to 134. Colour: Adults from the Indian Ocean with orange-red to reddish brown body, often with scattered small whitish or purple spots; purple network on head, maxilla, and lips; pectoral fins orange distally; membranes of soft dorsal, caudal, anal, and pelvic fins dusky: dorsal-fin rays orange distally; pelvic-fin tips blackish. Adults from the Pacific Ocean generally pale reddish to yellowish brown, covered with small brownish red or dark brown spots. Juveniles dark reddish brown to nearly black, the rear margin of the caudal fin and sometimes the pectoral fins whitish. A juvenile about 10 cm total length photographed in 30 m at Mauritius shows yellow spots on the head, scattered blackish spots (which could be quickly changed to pale greenish) on the body and oblique white stripes on the caudal fin somewhat like C. urodeta. Larger juveniles are brownish orange with scattered pale greenish spots on the body and a black spot between the upper and middle opercular spines.

Indo-Pacific from the east coast of Africa (from Socotra to Durban) to the Line Islands in the central Pacific; in the western Pacific, C. sonnerati ranges from southern Japan to southern Queensland. It is known from both continental and insular localities, including most of the islands in the tropical Indian and Pacific Oceans, but it has not been reported from the Red Sea or Persian Gulf. And it was not found at the Chagos Archipelago, despite an intensive survey there (Winterbottom et al., 1989).

C. sonnerati is a coral reef species usually caught in depths of 30 to 100 m, but at Madagascar it occurs in depths of 10 to 20 m. It feeds on fishes and crustaceans. According to Morgans (1982), females mature at about 28 cm standard length and males at about 34 cm.

Maximum total length recorded for C. sonnerati is 57 cm.

Allen (1985, in Fishes of Western Australia, p. 2205-2534. Pacific Marine Fishes Book 9. In: W. Burgess and H.R. Axelrod (eds): fig. 122) published an underwater photograph (labelled “Epinephelus multinotatus”) of what appears to be an unusually coloured specimen of C. sonnerati from the North West Cape of Western Australia. The ground colour is brownish, the head, body, and most of the fins covered with small dark brown spots; several large, irregular whitish blotches on the body and posteriorly on the head, those on the body aligned in 5 or 6 vertical or slightly oblique series, the last two on the caudal peduncle; a few scattered white spots on the body and more densely on the median fins. Judging from the differences in colour patterns of C. sonnerati in the Indian and Pacific Oceans, there are some genetic differences in the populations of these two areas; but Heemstra and Randall (1993) have not been able to find any morphological differences in specimens from these two areas.