On June 13th, Moul Thun, a 42-year-old fisherman from Kaoh Preah, a remote island in the Mekong River, in northern Cambodia, hooked an exceptionally large giant freshwater stingray. At 4 meters in diameter and weighing 660 pounds (about 300 kilograms) it proved to be the largest freshwater fish ever documented.

The BBC quotes Dr. Zeb Hogan, a biologist who leads Wonders of the Mekong, a USAID-funded conservation project, saying, “In 20 years of researching giant fish in rivers and lakes on six continents, this is the largest freshwater fish that we’ve encountered or that’s been documented anywhere worldwide.”

“Finding and documenting this fish is remarkable, and a rare positive sign of hope, even more so because it occurred in the Mekong, a river that’s currently facing many challenges,” added Dr. Hogan, who is also a professor at the University of Nevada, Reno.

“When record fish are found, it means the aquatic environment is still relatively healthy. This is in contrast to what we’ve seen in places like the Yangtze River, where scientists reported the extinction of the Chinese paddlefish,” Dr. Hogan said.

“The Mekong’s deep pools sustain life far beyond these impressive giants. Spawning in this critical habitat produces billions of fish every year which ensure the food security and livelihoods for millions of people in Cambodia and Vietnam.”

After the fisherman hooked the stingray – an endangered species – he contacted Wonders of the Mekong, which helped tag the female ray and release it back into the river.

The stingray is not the only Mekong River giant. A previous record was set in 2005 when fishermen in northern Thailand pulled a 646-pound Mekong giant catfish out of the river.

Thanks to Alaric Bond for contributing to this post.

Giant 300-kg stingray discovered in Cambodia dubbed “world’s largest” freshwater fish: Researcher