Giant Grouper Fact File
Credit: The Cosmonaut, CC BY-SA 2.5 CA <https://creativecommons.org/licenses/by-sa/2.5/ca/deed.en>, via Wikimedia Commons
Wild 37 years
Captive 37 years
The Largest Bony Fish on the Reef!
The giant grouper is the largest species of bony fish found in reef habitats with some individuals being recorded at weights of up to 600kg (1320lbs).
They are found in the Indo Pacific Ocean and will spend their time hunting for food which can be as large as sharks, rays or even sea turtles. All of the prey they consume is swallowed whole.
Most males have transitioned from being a reproductive female but recent research has shown that unlike most groupers some begin their life as a male and can spawn as soon as they become reproductively mature.
This species is increasingly threatened through hunting for food and the aquarium trade.
Read on to learn more about these fantastic fish.
What does the Giant Grouper look like?
Giant groupers are deserving of their name with a heavy, rotund body which is brownish across the length with light mottling across it.
Along the back is an elongated dorsal fin and a rounder tail fin. Along with the two front fins these are all colored yellow with small back spots patterning them.
They are the largest species of bony fish found in coral reef ecosystems. An average individual will measure 2.5m (8.25ft) long and weigh 400kg (880lbs) though individuals of up to 600kg (1320lbs) have been recorded.
How does the Giant Grouper survive in its habitat?
Large individuals will develop to be ciguatoxic which can help to discourage predators from attacking them.
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What does the Giant Grouper eat?
Giant groupers are carnivores. They primarily target crustaceans with the spiny lobster being a favored food. Other prey include fish, stingrays and small sharks. On occasion they have also been known to take small turtles.
The giant grouper will open its large mouth which suctions prey whole in to their mouth. All prey is eaten whole regardless of size. Inside the mouth are a number of needle-like teeth which are used to hold on to the prey.
Unconfirmed reports of this species attacking humans have been made.
Learn more about the Queensland Grouper in this video from
FishConsultGroup on YouTube
Where do you find the Giant Grouper?
This ocean going species has an Indo-Pacific distribution being found in areas of the Indian and Pacific ocean along the coastline of Australia, Africa and Asia.
Where can the Giant Grouper survive?
Most of their time is spent in shallow water and around the area of coral reefs. They are often sighted in lagoons, estuaries and harbors. On occasion they are seen in brackish water within estuaries.
They are often seen taking shelter in a cave.
Credit: Public Domain
How does the Giant Grouper produce its young?
Like most groupers these fish will start life as a female with some then transitioning to be males when they reach sexual maturity. Recent research has shown that this is not the case for all giant groupers though with some individuals being hatched as males.
This species is a broadcast spawner with the males fertilizing the eggs of multiple females. Spawning lasts for seven days. Initially the dominant male and female spawn with subordinate individuals joining as it progresses.
Juvenile giant groupers are colored yellow across the body with an irregular pattern of black bands found across their body.
Maturity is tied to size rather than age being achieved at 129cm (50.8in) long. This occurs around 6 years old in the wild.
What does the Giant Grouper do during its day?
These animals are considered solitary and it is most common to see them in the ocean on their own. Much of their life is spent in the same area.
Much of their time is spent on the ocean floor resting and waiting for food to come by which they can consume.
Credit: Public Domain
Predators and Threats
What stops the Giant Grouper from surviving and thriving?
Juveniles may be taken by larger fish but the adults have no natural predators apart from humans.
The giant grouper is the most widely distributed species of grouper. Naturally they are considered rare and numbers are declining. As a result in areas where overfishing has occurred the species has quickly been driven to extinction.
Due to a long generational length it takes a long time for populations to recover after being depleted.
Much of their decline comes through overfishing. They are targeted both for food and to obtain some parts for use in traditional medicines. The species is also kept in small numbers in the aquarium trade.
Increasingly these animals are being farmed which is helping to reduce pressure on their wild populations.
In Australia the species is given legal protection.
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This species may also be known as the Queensland grouper, bumblebee grouper, brindled grouper or mottled-brown sea bass.
They were first described for modern science during 1790.
A Queensland grouper was the first species of fish to undergo chemotherapy at the Shedd Aquarium in Chicago.
Credit: Public Domain
Burnie, D., 2011. Animal. 3rd ed. London: DK
Fennessy, S., Pollard, D.A. & Samoilys, M. 2018. Epinephelus lanceolatus. The IUCN Red List of Threatened Species 2018: e.T7858A100465809. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T7858A100465809.en. Accessed on 16 April 2022.
Bray, D.J. 2021, Epinephelus lanceolatus in Fishes of Australia, accessed 16 Apr 2022, https://fishesofaustralia.net.au/home/species/4672
Capuli, E., 2022. Epinephelus lanceolatus summary page. [online] FishBase. Available at: <https://www.fishbase.se/summary/6468> [Accessed 16 April 2022].
Waikīkī Aquarium. 2022. Giant Grouper. [online] Available at: <https://www.waikikiaquarium.org/experience/animal-guide/fishes/groupers/giant-grouper/> [Accessed 16 April 2022].
Dpi.nsw.gov.au. 2022. Giant Queensland groper. [online] Available at: <https://www.dpi.nsw.gov.au/fishing/closures/identifying/marine-or-estuarine-species/giant-queensland-groper> [Accessed 16 April 2022].
Usc.edu.au. 2022. Study finds surprising sex change secrets of giant grouper. [online] Available at: <https://www.usc.edu.au/about/usc-news/news-archive/2021/march/study-finds-surprising-sex-change-secrets-of-giant-grouper> [Accessed 16 April 2022].
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