The title of largest freshwater fish is usually given to the Mekong giant catfish or the arapaima. In June 2022 a giant freshwater stingray caught near Koh Preah in the Cambodian Mekong displaced them, weighing in at about 300 kilograms and measuring close to four metres from snout to tail.
The animal was measured by a research team, fitted with an acoustic tag and returned to the river alive. That combination, documented mass and release, is unusual for record fish and gives the measurement more weight than most historical claims.
Stingrays of this size are poorly known despite their bulk. They spend much of their time buried in sand in deep river pools, which makes them hard to survey. The population depends on stretches of large lowland river now under pressure from damming, sediment loss and fishing, and the species is assessed as Endangered.