Discovery of six rare Mekong giant catfish in Cambodia raises hopes for endangered species

Find is hopeful sign' the species, one of world's largest and rarest freshwater fish, is not at imminent risk of extinction

Six critically endangered Mekong giant catfish - one of the largest and rarest freshwater fish in the world - have been caught and released in Cambodia, reviving hopes for the survival of the species.

The underwater giants can grow up to 3 metres long and weigh up to 300kg. They are found only in south-east Asia's Mekong River but in the past inhabited the entire 3,044-mile (4,900km)-long river all the way from its outlet in Vietnam to its northern reaches in China's Yunnan province.