This is the largest freshwater fish. Just before midnight on November 13, fishers in Cambodia captured this individual of Mekong giant catfish, 8 ft long (2.4 meters long) ands weighing 450 pounds (204 kg).

"This is the only giant catfish that has been caught this year so far, making it the worst year on record for catch of giant fish species", said Zeb Hogan, a fisheries biologist at the University of Reno in Nevada, a National Geographic "emerging explorer", who launched the three-year Megafishes Project to document the world's giant freshwater fish.

After the data on the individual was gathered, the fish was released unharmed. Megafishes are "the real-life Loch Ness monsters and Bigfoots of the aquatic world.", said Hogan.

Mekong giant catfish can reach 3 m (10 ft) in length and be 350 kg (780 pounds) heavy. The giant vegetarian catfish was once abundant throughout Southeast Asia's Mekong River watershed, including the Tonle Sap River, where this individual was captured, close to Phnom Penh.

In the last 100 year, the overfishing of the Mekong giant catfish plummeted its numbers by 95-99 %, and now just a few hundred adult giant catfish could be left. Since 2000, no more than 10 fish have been captured accidentally throughout the whole Mekong basin. Once, hundreds of individuals were caught annually; in 2006 just one.

The picture was complicated by the fact that a species of Southeast Asian catfish, Pangasius krempfi, closely related to the Giant Mekong catfish is anadromous: it moves from coastal waters into rivers to spawn, just like salmons do, in an over 600 mi (1,000 km) journey from the South China Sea into the Mekong River. If the giant does the same, this is not very good news. "From the point of view of the fish, there's nothing worse than a dam. Dams block upstream migration, destroy spawning habitat, and can turn large stretches of river into ecological wastelands.", said Zeb Hogan.

"Everywhere around the world these large fish are in big trouble. In many places they're now so rare that the opportunity for documentation and study may soon be lost. The troubled story of the world's giant freshwater fish underlines the environmental crisis facing many rivers and lakes", he added.