Giant Grouper

Size

• Largest of all coral reef-dwelling bony fish.
• Common length up to 8 feet (2.5 m)
• One of the largest recorded was 9.8 feet (3 m) and weighed more than 882 lbs. (400 kg).

Color

• 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.

Body Composition

• Has a very large mouth that expands and protrudes to create a strong suction to draw in prey.
• Mouth has at least seven rows of teeth on 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.

Diet

• Consists of fish, sharks, juvenile sea turtles and crustaceans, including spiny lobster and mud crabs.

Feeding Behaviors

• 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 found on any one reef.
• Replacing older fish with a young individual takes many years.

• Occurs in the Indo-Pacific from the Red Sea to Algoa Bay, South Africa through the Hawaiian and Pitcairn islands and south to Australia.
• Found in tropical shallow reefs, caves, wrecks and estuaries commonly to 164 feet (50 m) deep. Full depth range is 13-328 feet (4-100 m).
• Most widely distributed of all the grouper species, but tends to be solitary with a “home” that they typically stay in.
• Juveniles tend to stay in sheltered areas like under ledges. Adults are found more offshore around piers, bridges, and wrecks.

• 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.
• Slow-growing and lives up to more than 50 years.

• “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.

• 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
• www.fishbase.org

  iucnredlist.org