Conservationists in Cambodia are working to save the giant catfish -- the largest freshwater fish in the world.

The critically endangered species is now protected by the Cambodian government. If fishermen on Cambodia's Tonle Sap River catches one of the fish, which can grow up to 10 feet long and weigh 650 pounds, they must turn it over to the Mekong Fish Conservation Project, National Geographic reported.

The fish is then tagged and released back into the river.

National Geographic said the giant catfish was once found throughout the Mekong River system but in the last century the population has declined 95 to 99 percent. Conservationist Zeb Hogan said there may only be a few hundred adult giant catfish left in the system today.

"These fish are on the verge of extinction, and that's a warning to us that there's something wrong with the river system," he told National Geographic. "The largest migratory fish are usually the first to disappear, but they won't be the last."

Copyright 2006 by United Press International