Around the world, freshwater "megafishes" face declining populations, increased threats from commercial fishing, shrinking habitats, and, in some cases, almost guaranteed extinction.

The "Megafishes Project" hopes to turn some of that around. The three-year project, sponsored by National Geographic and undertaken by University of Nevada, Reno researchers Zeb Hogan and Sudeep Chandra, aims to document and protect more than two-dozen giant fish species, many of which can weigh more than 200 pounds. The project was profiled in the journal Science (subscription required).

Species being studied by the Project include Thailand's Mekong giant catfish, China's paddlefish, and South America's Pirarucu. "Everywhere we look, the largest fish are disappearing," Hogan said in a University of Nevada press release. He says the world faces a "freshwater extinction crisis," and studying the world's largest fish can help benefit all other freshwater species.

Story by John Platt. This article originally appeared in Plenty magazine in July 2007 and now lives on MNN. Copyright Environ Press 2007

World's largest freshwater fish threatened
Concern is growing for 'mega fish' populations.