Chicago Tribune

WASHINGTON – It sounds like the world’s biggest fish story, but the National Geographic Society here confirmed it Wednesday: A giant, 646-pound catfish caught recently by Thai fishermen in the Mekong River is the largest freshwater fish ever recorded.

The grizzly bear-sized creature was examined and measured by associates of the Great Fishes Project, a special World Wildlife Fund and National Geographic Society effort to identify and save such aquatic giants from extinction before they succumb to overfishing, pollution and industrial development.

Comparing data, project members determined that this new catch was 11 pounds heavier than the previous record holder – another Mekong catfish.

“I expect we’re still going to find bigger fish than these,” said University of Wisconsin fisheries biologist Zeb Hogan, the project director. “It’s astonishing.”

According to Hogan, the Mekong has heretofore been a good habitat for such monsters because it is one of the deepest rivers in the world, reaching depths of more than 200 feet.

Don’t ask what lures or strength of line was used. The Thais employ special gill nets they trail 100 feet or so behind boats.

Though many of these big cats in the river are voracious eaters of other fish, this one was of a vegetarian species that subsists on underwater plants and algae.

Once measurements and photographs were taken, project members and other environmentalists urged that the giant fish be returned to the water. “But the Thai Department of Fisheries has a policy that requires extracting sperm or eggs from the fish first,” Hogan said.

The process took a day or more, and then the fish died, he said. It was sold for food and eaten.

Hogan, who was interviewed by telephone from Mongolia, said his search for an even larger fish would next take him to China’s Yangtse River.

New contenders for the title of the world’s largest freshwater fish include Mongolian salmon, giant sturgeon, giant lungfish, razor-toothed gar, the dinosaur-like arapaima, the giant freshwater sting ray and the ever-popular dog-eating catfish.

But Hogan is betting it will be the Chinese paddlefish, a creature indigenous to the Yangtze.

“It’s a long, slender fish that looks like a sturgeon,” he said, “except it has this long paddle-like (protuberance) extending from its snout. The fish uses it in smelling things. It looks something like a lollipop.”