An enormous stingray caught by a fisherman in Cambodia has become the world's largest fish.

The 13ft-long (3.96 metres) giant freshwater stingray weighing 661lbs (300kg) was hooked in the Mekong River in Stung Treng province in the northeast of Cambodia on June 14.

It was landed close ot the island of Koh Preah by local fisherman Moul Thun, 42, who then called a team of conservationists to help him handle his massive catch.

Biologists arrived and confirmed that the female stingray, nicknamed ‘Boramy' which means ‘full moon' in the local language, was the largest and heaviest on record.

It beats the previous record-holder for the world's largest fish, a catfish discovered in Thailand in 2005 which weighed 646 pounds (293kg).

Biologist Dr Zeb Hogan, who also hosted the National Geographic show ‘Monster Fish' said: ‘This is very exciting news because it is the world's largest fish.

‘It is also exciting news because it means that this stretch of the Mekong is still healthy. It is a sign of hope that these huge fish still live here.'

Biologists from the Wonders of Mekong research project weighed, measured, and tagged Boramy with a tracking device which sends signals to the team for research.

Data from the device will allow experts to document its behaviour while it moves along the vast river which runs through China, Myanmar, Laos, Thailand, Vietnam, and Cambodia.

The stingray was then released back into the river on June 20. It took at least a dozen people to haul it into the depths.

Wonders of the Mekong leader Zeb Hogan said that stingrays had suffered from 'habitat fragmentation from dams and overfishing'.

He added: 'About 70 per cent of giant freshwater fish globally are threatened with extinction and all of the Mekong species.'

Boramy was found only a month after another enormous 181 kg stingray was caught nearby.

The Mekong River is home to several species of giant freshwater fish but environmental pressures are rising.

Scientists fear major dam-building programs to generate hydro electric power - funded across the region by China, Japan and South Korea - in recent years may be disrupting spawning grounds.