The black grouper is a large hearty fish with a protruding lower jaw. It has an oblonged body shape and rounded margins on both the dorsal and anal fins. The caudal fin is squared-off, and the dorsal fin has 11 spines and 15-17 rays. The preopercule is rounded without the presence of a notch, which distinguishes it from the gag grouper. The black grouper has olive or gray body coloration along with dark rectangular blotches and small hexagonal bronze spots on its head and lower side. The borders of the soft dorsal, anal, and caudal fin is black or bluish; sometime there is an orangish edge along the pectoral fins.