Holy Mola: World's Heaviest Bony Fish Is An Absolute Unit At 2,744kg

Wait until you see these guys as babies, though.


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

world record heaviest fish
The hefty specimen topples the previous record holder by nearly half a ton. Image courtesy of Dr José Nuno Gomes-Pereira

They say mighty oaks from little acorns grow, and never has this saying been more apt than for the lifecycle of giant molas. These epic slabs for fish start out their lives like marine popcorn and grow to gargantuan sizes. Now, one specimen has become the heaviest bony fish in the world, weighing in at a hefty 2,744 kilograms (6,050 pounds).

Ocean sunfishes, as molas are also called, are known to be the heaviest living bony fishes and can stretch to over 3 meters (nearly 10 feet) in length. There are three species: ocean sunfish (Mola mola), giant sunfish (Mola alexandrini) and the hoodwinker sunfish (Mola tecta). They spend their lives moving between the deep ocean and sea surface where they can be found basking side-up in an effort to warm up and get a parasiticide treatment in the form of grooming gulls.


In December 2021, a dead giant sunfish was found floating near Faial Island off Horta Harbor in the Azores archipelago, Portugal. The absolute unit was heaved aboard by the Azores marine strandings network (Rede de Arrojamentos de Cetáceos dos Açores) and weighed back on land with the aid of a forklift truck.

world's heaviest fish
The giant sunfish was so enormous it could only be weighed with the aid of a forklift truck. Image courtesy of Dr José Nuno Gomes-Pereira

The weigh-in revealed it was 2,744 kilograms with a body length of 3.59 meters, making it the heaviest bony fish on record.

“The M. alexandrini reported here is the heaviest extant teleost specimen reported to date,” wrote the scientists behind the discovery. “It exceeds by nearly half a ton (444 kg [979 pounds]) the largest previously known specimen (2300 kg [5,070 pounds]), caught off Kamogawa, Japan in 1996... Giant sunfishes M. alexandrini can thus reach more than twice the maximum weight of its congeneric, the ocean sunfish M. mola (heaviest record 1320 kg [2,910 pounds]).”

As for what killed the ocean giant, researchers working on the discovery aren’t yet sure. A dent on its head with signs of paint indicates the animal was hit by the keel of a boat at some point, but whether this happened pre- or post-mortem isn’t clear.


The team hopes to continue working on the specimen to see what new insights it could yield about this rare, elusive, and – evidently – world-record-breakingly enormous species. For those not yet blessed by the sight of giant sunfish larvae, please feast your eyes upon it in all its adorable popcorn-like wonder. And as if that isn’t cute enough, in their infancy these oceanic slabs get the zoomies, too.

Who said absolute units couldn’t be precious?

The discovery was published in the Journal Of Fish Biology.


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