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CRITTER: Meet hapu‘u the Hawaiian 900-pound giant grouper

Scuba diving with eight giant groupers that weigh between 500 to 800 pounds is just a thrill, and you really feel like you are back in the time of the dinosaurs!

These monster fish have no fear of humans, and they are super rare in the main Hawaiian Islands. But from time to time one will show up and get caught by a local fisherman.

Back in the 1980s a 554-pound hapu‘u was caught in Kihei and a seven-foot giant was speared off Lehua near Kaua‘i.

Hapu‘u tend to like the colder NW Hawaiian Islands water, and once a year many of these huge fish will congregate in one area for breeding. Hapu‘u is an ambush predator and usually feeds on the bottom for anything it can suck into its mouth. They feed on smaller fish including sharks! They also eat octopus and lobster. When they find a lobster back in a cave or crack the giant grouper rapidly opens its mouth, sucking the lobster in and swallowing it whole! This happens so fast that it looks like a giant rock just caused a big lobster to disappear!

Hapu‘u live all throughout the tropical Pacific, but are quite rare, and most divers will never get to see one. Giant groupers also like to eat moray eels. Hawaiian has more moray eels than anywhere else in the world I have dove at, and that is due to the lack of these big predator fish. I have dove with the giant grouper off of the West Coast of the USA, Florida and the Bahamas, and in grouper habitat it is rare to see a moray eel out swimming around on the reef, as they could get sucked down by a 900-pound grouper. In Hawai‘i we often see five to 10 moray eels on a single scuba dive, and many of those are out free swimming because there are a lack of large predators in Hawai‘i to eat them.

Hapu‘u are harmless to humans unless you are out spearfishing or collecting lobsters. I was out collecting lobsters one day when a 400-pound hapu‘u showed up and started following me around like a giant puppy dog. I pulled a lobster out of a hole and the giant grouper sucked it right out of my hand in a split second, sucking in part of my arm with it! After that I decided to never again do any fishing anywhere near these giant fish!

You can see hapu‘u in action on my YouTube channel at Underwater2web in my documentary movies I shot in California, Florida and the Bahamas.


Terry Lilley is a marine biologist living in Hanalei. He is co-founder of Reef Guardians Hawai‘i, a nonprofit on a mission to provide education and resources to protect the coral reef. To donate to Reef Guardians Hawai‘i go to
Source: The Garden Island

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