The giant grouper is the largest of all reef-dwelling bony fish, growing up to 9 feet (2.7 m) in length and weighing up to 660 pounds (300 kg).
  • Size

    6.2 feet (1.9 m)
  • Diet

    Fish, sharks, juvenile sea turtles and crustaceans
  • Range

  • Habitat

    Tropical shallow reefs, caves, wrecks and estuaries

Physical Characteristics

  • Largest of all coral reef-dwelling bony fish.
  • Common length of 6.2 feet (1.9 m), with a maximum length of 9 feet (2.7 m).
  • One of the largest recorded was 9.8 feet (3 m) and weighed more than 882 lbs. (400 kg).
  • Has a very large mouth that expands and protrudes to create a strong suction to draw in prey.
  • The mouth has at least seven rows of teeth in the middle of the lower jaw.
  • The giant grouper’s eyes function effectively in dim light, which gives it an advantage over its prey during dawn and dusk feeding times.
  • Eyes also rotate so grouper can see approaching prey without moving its head.
  • Juvenile giant grouper are bright yellow with large, irregular black or dark brown bars.
  • As adults, irregular patterns break up and their coloring becomes a muted, mottled olive-gray.


Animal Fact

Giant groupers can reach up to 9 feet (2.7 m) in length.

Diet / Feeding

  • Consists of fish, sharks, juvenile sea turtles and crustaceans, including spiny lobsters and mud crabs.
  • Ambush predator that lies in wait while hiding in holes, crevices and reef overhangs.
  • Swallows food whole.
  • Occupies the upper end of the food chain.
  • Few reside in each area; few are found on any one reef.


Range / Habitat

  • Occurs in the Indo-Pacific from the Red Sea to Algoa Bay, South Africa through the Hawaiian and Pitcairn islands and also Australia.
  • Found in tropical shallow reefs, caves, wrecks and estuaries commonly to 164 feet (50 m) deep. The full depth range is 13-328 feet (4-100 m).

Reproduction & Growth

  • Protogynous hermaphrodite; starts out life as a female and can later change gender to become male.
  • Does not reach sexual maturity until it is about 20 years old. Fishing usually removes the largest, and therefore oldest, fish first.

Conservation Status

  • “Data Deficient” on IUCN Red List.
  • The population is thought to be declining 20 percent rate every ten years.
  • Populations of this species have been drastically reduced worldwide due to overfishing but long-term quantitative data are not available across a large portion of its range.

Additional Information

  • Slow-growing and lives up to or beyond 50 years.
  • Other common names for this species are “Queensland grouper” and “brindle bass.”


  • Encyclopedia of Fishes. 2nd Edition, pgs. 195 -199
  • Fishes of the Great Barrier Reef. Randall, J. E., pg. 109
  • Fishes of the Tropical Eastern Pacific. Allen, G. R., pg. 106
  • Reef Fish. Thresher, R. E., pgs. 153 -155
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