Scientists say that a 660-pound stingray caught in the Mekong River in Cambodia is the biggest freshwater fish ever documented.

It unseated the previous record-holder, a 646-pound Mekong giant catfish caught in Thailand in 2005, The AP reports.

The Mekong River is rich in biodiversity, but overfishing, dams, and pollution threaten its fragile ecosystem, reports the AP. It flows from the Tibetan Plateau through China, Myanmar, Thailand, Laos, Cambodia, and Vietnam.

“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,” said biologist Zeb Hogan.

Hogan leads Wonders of the Mekong, a USAID-funded conservation project, and is the host of the National Geographic television show Monster Fish with Zeb Hogan.

“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 Hogan, who is also a research associate professor at the University of Nevada in Reno.

The conservation project collaborates with the Cambodian Fisheries Administration to establish a network of anglers who notify researchers when they catch giant or endangered fish.

On June 13, a local fisherman on Koh Preah Island called researchers to say he had caught a “very big” stingray measuring 13 feet long and 7.2 feet wide.

The stingray was returned to the river after being fitted with an acoustic tag to track its future movements.

It vanished into the muddy waters of the Mekong around dusk, when the moon was already visible in the sky, according to Hogan. The fish was named “Boramy,” which means “full moon” in the Cambodian language of Khmer.

“The stingray find is evidence that the natural world can still yield new and extraordinary discoveries and that many of the largest aquatic creatures remain woefully understudied,” Hogan said.

The giant freshwater stingray is an endangered species. The fish is the second giant stingray examined by the team since May — the earlier one weighed 399 pounds.

“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,” Hogan said.