For 17 years, Zeb Hogan, a biologist, has been searching for the world’s largest freshwater fish. On June 13, his team found it — a giant freshwater stingray, or Urogymnus polylepis.

The ray, hauled out of the murky waters of the Mekong River in Cambodia, measured four metres in length before it was returned to the river. And at 300kg, it was 7kg heavier than a Mekong giant catfish caught in Thailand in 2005. Hogan said he had previously established that freshwater fish as the largest ever caught.

While this species of giant stingray has an extremely dangerous venomous barb that can reach 30cm in length, they are not usually a threat to humans. More often, they wind up in the market as a source of cheap protein.

Fishers in Cambodia first alerted Hogan and his team at Wonders of the Mekong Project, which works to protect the Southeast Asian river’s aquatic diversity and is sponsored by the US Agency for International Development, that they had caught a stingray larger than anyone had ever seen. Team members rushed to the small river island, called Koh Preah, and lined up three industrial scales. Using a tarp, they hoisted the stingray out of the water and onto the scales to verify its weight.

The discovery comes less than a month after another giant stingray — that one weighing 180kg — was caught and released nearby. Two other enormous rays have also been caught this year.

“The fact that the world’s largest freshwater fish was caught in the Mekong is remarkable,” Hogan said. “This is a heavily populated region, and the river faces a ton of challenges, including lots of fishing.”

This article originally appeared in the New York Times.