A Cambodian fisherman was in for a surprise last week when he landed what researchers believe could be the world's largest freshwater fish ever caught.
Moul Thun, 42, caught the giant stingray near a remote island on the Mekong River last week (June 13) using only a hook and a line.
The next day, he reached out to researchers to help him measure, weigh and tag the massive creature, which turned out to be over 13 feet long and weigh 661 pounds.
Workers with the Wonders of Mekong were already in northern Cambodia, where they were installing underwater receivers as part of a project to track wildlife in the area. They had already been in touch with local fishermen, telling them to get in touch if they landed any particularly big animals.
"It’s a particularly healthy stretch of the river with a lot of deep pools — pools up to 90 meters deep," said researcher Zeb Hogan, a fish biologist from the University of Nevada, to NBC News.
"We started focusing on this area as a stretch of river that’s particularly important for biodiversity and fisheries, and as a last refuge for these big species," he added.
A post on the organization's official Instagram page read: "The world record for the largest freshwater fish ever discovered on earth has just been broken! A 661-pound giant freshwater stingray was hooked by a fisher in Cambodia in a rural stretch of the Mekong River."
It continued: "Fortunately, the fisher contacted the Wonders of the Mekong team, setting into motion the first-ever acoustic tagging effort of a freshwater stingray. For the last month, Wonders of the Mekong team members, along with FISHBIO and others, have been deploying a network of acoustic receivers throughout the Cambodian Mekong basin.
"This new network will allow scientists to observe this rare fish species and learn about its movement and behavior!"
The team paid the market price for the giant stingray, then tagged it before releasing it back into the river. Researchers are optimistic that tracking the movements of the stingray will help them learn more about it as a species. Hogan explained that the catch "highlights how little we know about a lot of these giant freshwater fish."
"You have a fish that’s now the record holder for the world’s largest freshwater fish, and we know little about it," he said.
Giant freshwater stingrays are relatively mysterious creatures. According to National Geographic, they can reach up to 16.5 feet long. They are bottom feeders who dwell on river beds, burying themselves in mud and eating shrimps, mollusks, clams, and other small fish.
Although they do not readily attack humans, the river giants can still pose a real danger to people if they feel threatened by them. Each ray is armed with a sharp barb on the end of its tail which can easily penetrate human skin and bone and emits a poisonous toxin.
