Goliath grouper are usually brownish yellow, gray or olive with small dark spots on the head, body and fins. Goliath can have three or four faint vertical bars on the sides of the body that are formed in an irregular pattern on fish less than 3 feet long. Strikingly patterned juveniles with a series of dark, irregular vertical bands and blotches inhabit mangroves and brackish estuaries, especially near oyster reefs. The goliath grouper is notable as one of the few groupers found in brackish waters.
Occurring in shallow, inshore waters to depths of 150 feet, goliath grouper prefers areas of rock, coral and mud bottoms. This fish is solitary by nature, with the adults occupying limited home ranges. It is territorial near areas of refuge suck as rocky outcrops, wrecks and ledges, displaying an open mouth and quivering body to intruders. Additional warning may be delivered in the form of the goliath grouper’s ability to produce a distinctly audible rumbling sound generated by the muscular contraction of the swim bladder. This sound travels great distances underwater and is also used to locate other goliath grouper.
Goliath grouper feed mainly on crustaceans, fishes, octopus and young sea turtles. Goliath grouper feed by ambushing their prey with a quick rush and snap of the jaws. Although prey is usually swallowed whole, these fish have sharp teeth for capturing prey.