Giant 300kg stingray breaks record as largest freshwater fish ever discovered

The world’s largest recorded freshwater fish has been discovered in the Mekong River in Cambodia, say scientists.

The giant stingray measured almost 4 metres from snout to tail and weighed slightly under 300 kg, according to a statement on Monday by Wonders of the Mekong, a joint Cambodian-US research project.

The previous record for a freshwater fish was a 293 kg Mekong giant catfish, discovered in Thailand in 2005, the group said.

Freshwater fish are defined as those that spend their entire lives in freshwater, as opposed to giant marine species such as bluefin tuna and marlin, or fish that migrate between fresh and saltwater like the huge beluga sturgeon.

A team of scientists were called to examine the fish before it was released back into the river.

The stingray's catch was not just about setting a new record, Wonders of the Mekong leader Zeb Hogan said in an online interview with the University of Nevada.

“The fact that the fish can still get this big is a hopeful sign for the Mekong River,” he said, noting that the waterway faces many environmental challenges.

The Mekong River runs through China, Myanmar, Laos, Thailand, Cambodia and Vietnam. It is home to several species of giant freshwater fish but environmental pressures are rising.

In particular, scientists fear a major programme of dam building in recent years may be seriously disrupting spawning grounds.

“Big fish globally are endangered. They’re high-value species. They take a long time to mature. So if they’re fished before they mature, they don’t have a chance to reproduce,” Hogan said.

“A lot of these big fish are migratory, so they need large areas to survive. They’re impacted by things like habitat fragmentation from dams, obviously impacted by overfishing. So