The largest freshwater fish to date has been discovered in northern Cambodia.
A fisherman caught the female ray, which weighs around 300 kilos and is almost four meters long, in the Mekong – the river crosses six countries and flows into the Gulf of Thailand.
Unnerved by his catch, the fisherman contacted a team of researchers currently installing sensors in the river to study the movements of freshwater fish in the region as part of the Miracle of the Mekong project.
Natural pools up to 90 meters deep
The catch shows how little we know about freshwater rays, says Zeb Hogan, a University of Nevada fish biologist who is involved in the Miracle of the Mekong project.
"We have a fish here that now holds the record for the world's largest freshwater fish, and we know next to nothing about it."
According to the researcher, the trapping site is an extremely healthy section of the Mekong, with natural pools up to 90 meters deep.
"It's a glimmer of hope that these big fish aren't extinct yet," says Hogan.
Nevertheless, the site is one of the last habitats for such animals.
Christened Boramy (full moon), as the circular lady ray has now been christened in the Khmer language, is doing well and was released after she had a sensor fitted.
Their movements should now provide the researchers with important insights into the lifestyle of large freshwater fish.
The animal species is not dangerous.
The creature has a mouth "the size of a banana," according to Hogan.
But there are no teeth in it, but suction cups with which the ray catches mollusks and small fish at the bottom of the river.