World’s largest freshwater Stingray weighing up to 300-kg discovered in Mekong River, stunned scientists

Largest freshwater stingray ever recorded found in Cambodia. (Image: Guinness Book of World Records)

• A 300-kg stingray in Cambodia is now the largest freshwater fish.
• Scientists tagged and released a stingray to track its movements.
• Endangered stingray showcases Mekong River's biodiversity.

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A massive 300-kilogram giant freshwater stingray discovered in Cambodia’s Mekong River has officially become the largest freshwater fish ever recorded, scientists said.

The enormous ray, measuring nearly 4 metres from snout to tail, surpassed the previous record of a 293-kg Mekong giant catfish. This catfish was caught in Thailand in 2005. The discovery highlights the remarkable biodiversity still hidden within Southeast Asia’s rivers.

A record-breaking catch in Cambodia

The giant stingray was accidentally caught by fishermen in the Mekong River in northern Cambodia. Realising its extraordinary size, they alerted researchers working with the Wonders of the Mekong conservation project.

Scientists rushed to the site and carefully weighed, measured and documented the enormous fish, confirming it as the largest freshwater fish ever recorded.

The ray tipped the scale at about 300 kilograms (660 pounds), making it heavier than the previous freshwater record holder.

Guinness Book Of Record the World's Largest Stingray

The animal was identified as a giant freshwater stingray. It is scientifically known as Urogymnus polylepis. Researchers connected to the Wonders of the Mekong project, supported by the University of Nevada, Reno, were called in to examine the catch.

Shortly afterward, Guinness World Records reviewed the documentation and recognized the specimen as the largest freshwater fish ever recorded.

Tagged and released back into the river

Instead of keeping the rare animal, researchers attached a tracking tag to the stingray before releasing it back into the river.

The tag will allow scientists to monitor its movements and migration patterns, helping researchers better understand the secretive species that lives along muddy riverbeds.

Giant freshwater stingrays can grow to extraordinary sizes but are rarely seen because they spend most of their lives buried in sediment at the bottom of large rivers.

What makes the Mekong River unique?

Stretching over 4,300 kilometres across Southeast Asia, the Mekong River is one of the most biodiverse rivers on Earth. It supports hundreds of fish species, including some of the largest freshwater animals ever known.

Scientists say the discovery proves that the river still holds extraordinary wildlife despite increasing environmental pressures.

Are scientists concerned for this fish? 

Despite this remarkable find, the giant freshwater stingray is considered endangered. The species faces several threats such as overfishing, hydropower dam construction, sand mining and habitat degradation.

Researchers warn that protecting the Mekong River ecosystem is crucial to ensure that these giant freshwater species continue to survive.

A rare glimpse of river giants

For scientists, the discovery represents a rare opportunity to study one of the planet’s most mysterious freshwater giants.

It also serves as a reminder that even in heavily used rivers like the Mekong, record-breaking wildlife may still be hiding beneath the surface.