The Mekong is an exceptional river in many ways. In terms of fish biodiversity, it is the world’s second richest river after the Amazon (www.fishbase. org). With 6 to 18% of the global freshwater fish catch, it is also home to the largest freshwater fisheries in the world. The productive Mekong fisheries are essential to the food security of the 60 million people of the Lower Mekong Basin. Fish contributes 81% of the population’s protein intake in Cambodia and 48% in Laos. Mekong inland fisheries also provide employment to 1.6 of the 14 million Cambodians. In the Mekong Delta in Vietnam, 60% of the people are part-time fishers (An Giang province) and 88% of 'very poor' households depend on fisheries. The combination of high fish biodiversity, high productivity, high exploitation rate and long distance migrations makes dam development a major concern in the Mekong Basin.