Scientists Catch the World’s Largest-Ever Freshwater Fish

Scientists in Cambodia have caught what’s believed to be the world’s biggest-ever freshwater fish. Prehistoric species notwithstanding, the 300kg stingray landed in the Mekong River is the largest freshwater fish ever documented. And it wasn’t just heavy. The river monster was also huge, measuring 3.98m long and 2.2m wide.

World’s biggest freshwater fish

Landed just less than a week ago on the 13th of June, the massive stingray usurps the previous record-holder, a 293kg giant catfish. The catfish in question also came from the Mekong, although further up the river in Thailand. Caught in 2005, it’s taken almost two decades for anyone to land a bigger fish.

At least, that’s as far as we know because there’s no official record-keeping for the world’s biggest freshwater fish. That said, there’s little surprise that both fish in question came from the Mekong, which is massively rich in biodiversity. In addition to Cambodia and Thailand, the Mekong also flows through China, Myanmar, Laos, and Vietnam.

A fragile ecosystem

Unfortunately, overfishing, the relentless building of dams, and widespread pollution all now threaten the Mekong’s fragile ecosystem. At the same time, finding and documenting fish like the recently caught 300kg Mekong stingray isn’t just a remarkable feat, according to scientists. It’s also a rare and positive sign of hope, they report.

That’s because it demonstrates the natural world and its rivers and other aquatic environments—even when struggling with dams, overfishing, and pollution—can still produce extraordinary discoveries. Scientists also say it shows how woefully understudied many of the largest aquatic creatures are, even in the 21st century.

300kg giant stingray

The fish in question was caught close to Koh Preah island and studied as a part of a local conservation project. The project, Wonders of the Mekong, works alongside the Cambodian Fisheries Administration and a network of fishermen committed to alerting scientists and researchers to unusual catches – namely giant or endangered fish species.

Thankfully, the monster stingray was released back into the river after scientists had fitted an acoustic tag to track its onward movements up and down the Mekong. Unfortunately, the Mekong’s giant freshwater stingrays are known to be an endangered species. The last time Wonders of the Mekong’s team encountered one was earlier this year – a relative tiddler weighing just 181kg.

Conservation woes across Asia

The discovery of Cambodia’s record-breaking 300kg giant stingray still bodes well for the Mekong – something that cannot be said of many other rivers in the region. A perfect case in point is the Yangtze River in China. Two years ago, scientists reported that the Yangtze’s Chinese paddlefish, another river giant growing up to 7 metres in length, had sadly succumbed to extinction.

The last confirmed sighting of the enormous freshwater oddball was almost two decades ago, in 2003. It’s thought that the Chinese paddlefish, a once-common sight on the Yangtze, died out sometime between 2003 and 2010.

Around for over 200 million years, scientists have blamed overfishing and dam construction for its demise. It’s a sad reality and one that further serves to highlight the risks faced by species like the Mekong’s giant freshwater stingray.

Photo credit: @mekongwonders