Cambodia Fisheries personnel release a Mekong giant catfish in 2005. The 5-foot (1.5-meter) megafish weighed nearly 100 pounds (50 kilograms).
In terms of biodiversity, the Mekong River is second only to the Amazon among the world's great rivers. As a home to more than 1,000 fish species, the Mekong supports the world's largest freshwater fishery, and it provides food and income—through fishing, farming, ecotourism, and other jobs—for many of the 65 million people who live in the Lower Mekong basin.
The Mekong is unique among the world’s large rivers because "the fish diversity is extremely high, the diversity of migratory species is extremely high, and human dependence upon these species for fisheries is extremely high," said Peter McIntyre, a freshwater conservation expert at the University of Wisconsin-Madison.
"You put all of that together, and putting a large dam in the Mekong is likely to cause major problems."
(Related news: “New Mekong Species Photos: Fangless Snake, Bald Bird.”)