Until recently, the record of the largest freshwater fish in the world was held by a Mekong giant catfish (Pangasianodon gigas) which was caught on the Mekong River in Thailand in 2005. It measured 2.7m from head to tail, and weighed 293kg.


However, in June 2022 a Cambodian fisherman fishing on the Mekong River caught a female giant freshwater stingray (Urogymnus polylepis) which claimed the title of the largest freshwater fish in the world. She measured a remarkable 3.98m in length (tail included) and 2.2m in width. And she weighed an astonishing 300kg – roughly equivalent to a grizzly bear.

She was named ‘Boramy’, which means ‘full moon’ in the local Khmer language, due to her shape and the evening time of her release. She was measured and tagged by scientists working in the US-Cambodian Wonders of the Mekong Project in collaboration with the Cambodian Fisheries Administration, and released back into the river.

“This is an absolutely astonishing discovery and justifies efforts to better understand the mysteries surrounding this species and the incredible stretch of river where it lives,” said Dr Zeb Hogan, a giant fish expert, presenter of the Monster Fish TV series and director of the project, to the Guinness World Records.

“While fishermen in Cambodia tell stories of stingrays up to 500 kg [1,100 lb], we've never been able to verify these reports. It's very fortunate that the 'Wonders of the Mekong' team was on site, that the fishermen called us, and that the stingray was tagged and released.”

“I hope that this catch raises awareness about the extraordinary animals that live in the Mekong River, the river's globally significant fisheries, and the importance of a healthy Mekong River to millions of people in Thailand, Laos, Cambodia and Vietnam.”

The giant freshwater stingray, also known as the whipray, is found in large rivers and estuaries, where it lives at the bottom and feeds on small fish and invertebrates. Its current distribution includes Southeast Asia and Borneo, though it’s thought that historically it was more widely distributed across South and Southeast Asia.

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The species is listed as Endangered on the IUCN Red List, facing a variety of threats including hunting for meat and recreation, capture for aquariums, and habitat degradation and fragmentation.

What is Europe’s largest freshwater fish?

There appears to be no definitive answer. Some scientists bestow the honour on the wels catfish (a 127kg individual was caught in Italy in 2015); others claim the title belongs to the Beluga sturgeon.

Still others nominate the mangar, a little-known relative of the common barbel and a voracious predator whose name translates as ‘pike-like wolf- barb’. This behemoth inhabits the Tigris– Euphrates river system, and is the biggest freshwater fish in Turkey – one caught in 2001 apparently weighed in at 111kg.


Main image: A female giant freshwater stingray. © Sinsamout Ounboundisane/FISHBIO


Megan ShersbyNaturalist, writer and content creator
Sarah McPhersonFeatures editor, BBC Wildlife Magazine