Fishermen who like to "noodle" their catfish-catch them by ramming a hand in their mouths and jerking them from their holes-will probably not want to pursue their sport on Cambodia's Mekong River. Here the catfish grow to more than 600 pounds. Drifting with them in the slow, muddy waters are supersize carp, 14-foot freshwater stingrays, and an incredible variety-over 150 species-of smaller fishes.
"The Mekong seems to have more giant fish than any other river in the world," says Zeb Hogan, a fisheries biologist from the University of California who is studying the fish and trying to find ways to help them survive into the future.
Hogan travels by boat every day along the river just outside the Cambodian capital of Phnom Penh, a city of over 1 million people, visiting fishermen and buying giant fish.
"We pay the local fishermen market price for the giants, and then we tag and release them," Hogan says. The fish, he has learned, leave the Mekong at the beginning of the rainy season and travel up the Ton Le Sap River to Ton Le Sap Lake. "The lake is huge during the rains, and the fish feed in the flooded forests and grasslands."