Villagers gather around a Giant Catfish caught in a “Li” of Sahong Channel. The Giant Mekong Catfish (Pangasianodon gigas) is probably the largest freshwater fish in the world. It is endemic to the Lao, Thai, Chinese and Cambodian stretches of the Mekong River, where it is in danger of extinction due to overfishing as well as a drop in the water quality due to develop-ment and upstream damming.