Locals were mystified to find a massive Amazon rainforest fish dead on the bank of a lake next to the Angkor Wat temple in Cambodia.

The giant dragon fish, or Arapaima, from South America shocked villagers when it turned up lifeless in Krakan village, Siem Reap province, on November 3.

Residents gathered on the banks to inspect the leviathan, which weighed a whopping 70 kilograms.

It is suspected to have belonged to a private collector who dumped it into the pond when it grew too big for them to take care of.

Authorities are now investigating the cause of the fish's death after it floated onto the shore.

Resident Muysong Sam, who works at the temple, told local media: 'I know that some people like to keep these fish as pets but they are very expensive. I walk past the pond every day and had not seen this before, so I think it has only been put here recently.'

A similar dragon fish weighing 30kg was found dead in the same pond in May 2020. They have also been seen in neighbouring Thailand after being released from private aquariums.

It is unlikely they would be able to survive for long in Cambodia's tropical climate alongside native species of fish due to the difference with the Amazon rain forest.

The Arapaima fish is native to the Amazon and is among the largest freshwater fish species, capable of reaching up to 15 feet in length.

They are sometimes hunted down for their meat, with their populations declining due to overfishing and the destruction of their habitat.