Death Ray

"Jeremy heads to the Mekong River in Thailand in search of one of the world's largest and most terrifying river fish - the Giant Freshwater Stingray. Armed with a venomous 18-inch barb on the end of its whip-like tail, this mysterious 1,300-pound predator tests Jeremy to his physical limit, snapping his marlin-class rod, ripping his bicep, and luring him into a confrontation with the border police. In this epic quest, Jeremy witnesses a remarkable event in the life of one of these river monsters and sheds some light on the natural history of this elusive beast."

Synopsis
Jeremy Wade ventures to the Mekong River in Thailand to find what may be the largest freshwater fish: the giant freshwater stingray. Armed with a 10 inch, venom-coated barb, this fish grows to 16 feet long and its venom has no known antidote. Unlike most South American freshwater stingrays (which usually don't get very big and deadly), this creature is a true monster. This behemoth can nearly glue itself to the bottom of the river, and once Jeremy hooks one, it may be his biggest challenge yet.

In this adventure he also meets other giants of Southeast Asia: the gentle Mekong giant catfish, a close relative of the well-known iridescent shark. The giant barb he caught in this trip only appears on some photographs made during filming, but not in the actual episode or the extended cut.