Join National Geographic Explorer Zeb Hogan on a quest to save some of the biggest freshwater fish in the world. We’ll track the elusive and legendary freshwater stingray in northern Cambodia. These giant stingrays grow to mammoth proportions and Zeb Hogan gets up close and personal with one of them. Then, Hogan is off to Thailand to study the giant Mekong catfish, which can grow to be as large as a grizzly bear! Today, the giant Mekong catfish are in danger of extinction due to overfishing and rapid development along the great rivers of Asia. Using underwater tracking devices to locate their spawning grounds, Hogan attempts to unravel the mystery of where these titans of the deep breed. Then, witness a rare capture of a giant Mekong catfish and watch Hogan persuade local fisherman to release the endangered creature back into the wild.