Captured just before midnight on November 13 by fishermen in Cambodia, the Mekong giant catfish was 8 feet long (2.4 meters long) ands weighs 450 pounds (204 kilograms).
"This is the only giant catfish that was so far this year, making it the worst year on record for catching fish species giants," said Zeb Hogan (right), a fisheries biologist at the University Reno in Nevada.
After collecting data on fish, Hogan released unharmed.
Siluro giant once were abundant throughout Southeast Asia, the Mekong River Basin, including the Tonle Sap River-home of the fish in these exclusive pictures taken near Phnom Penh.
But in the last century, the giant Mekong catfish population has declined by 95 to 99 percent, scientists say. Only a few hundred adult giant catfish can stay.
Since 2000 five to ten fish have been caught accidentally every year across the Mekong area.
Earlier this year, Hogan launched the three-year period Megafishes Draft paper by world giant freshwater fishes (See photos of other giant fish.)
