Attack of the Goliath Grouper

When one thinks of being attacked by a fish in the ocean, sharks are usually the animals that come to mind. However, in terms of actual number of attacks on divers, the goliath grouper gives sharks a run for their money.

In fact, this fish has been known to steal food from aggressive sharks feeding on prey on the ocean bottom. The Atlantic goliath grouper (Epinephelus itajara) is a territorial fish, and many of the attacks may simply be defense of its territory. In these cases, it is likely the diver's fault for unknowingly entering the territory of the goliath grouper.

Although the attack may be defensive, this massive fish has numerous sharp teeth that can cause significant harm to an unwitting diver or any other organism entering its home range. The goliath grouper is considered one of the largest fish in the sea bass family. It will typically reach the size of a large motorcycle (400 to 800 pounds) and can attain lengths of over 8 feet.

The largest grouper ever caught on a rod and reel was 680 pounds. These fish get so large in part because they have a long lifespan. The oldest fish recorded from analyzing bone rings was 37 years old. As they age their growth rate slows down, but like most fish growth, never completely stops until the fish dies.

This monster is usually found in relatively shallow water down to 150 feet and around rock outcroppings and coral reef crevices on the continental shelf. They stay in dark holes and crevasses, waiting for their prey to swim within reach. Goliath groupers eat crustaceans, other fish, octopuses and young sea turtles. Young groupers are in turn preyed upon by large fish such as barracuda, moray eels and large sharks.

Unsubstantiated stories about the Goliath grouper are numerous. For example, The New York Times reported in 1895 that a fisherman caught a 1,500-pound Goliath grouper in the Gulf of Mexico. In the 1950s, two children jumped off a bridge in the Florida Keys but only one came up; the other child was said to have been eaten by a Goliath grouper. There are other stories about spearfishermen being attacked and killed.

It is not always certain who is the hunter and who is the hunted. Some less spectacular stories are known to be true. The second author's older brother worked as a commercial deep sea diver on oil rigs in the Gulf of Mexico. A Goliath grouper aggressively chased several divers from around one oil rig until the brother finally had to go down and show the fish that humans are 'the boss' by banging on it with a huge 20-pound box wrench. It took several hits from the wrench before the huge fish moved off.

Except for its size, the goliath grouper is similar to the regular grouper that is served in many restaurants around the world. Because groupers form large spawning aggregations in the same locations year after year they are vulnerable to mass harvesting. The goliath grouper is now protected by conservation efforts around the world. It is recognized as a critically endangered species by the International Union for Conservation of Nature (IUCN).

Sport fishing for these fish is not illegal, but catch and release must be practiced. This does not fully protect the fish because of illegal harvesting of the species. This giant attacking fish may not be as deadly as sometimes portrayed, but they are definitely a monster of the deep which a diver must approach with caution.

Experienced divers may consider themselves fearless towards anything in the water, but when faced with a monster goliath grouper, their diving skill and nerve may be tested. The goliath grouper has survived millions of years by defending its own, even if this means aggressively taking on humans. For more information contact the ASU Dept. of Biological Sciences at

Story Jacob Clanton and Dr. Richard S. Grippo

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