Ethnic Cham Muslim people pass the time near their boats on banks of Mekong river in Phnom Penh July 29, 2013. About 100 ethnic Cham families, made up of nomads and fishermen without houses or land who arrived at the Cambodian capital in search of better lives, live on their small boats on a peninsula where the Mekong and Tonle Sap rivers meet, just opposite the city's centre. The community has been forced to move several times from their locations in Phnom Penh as the land becomes more valuable. They fear that their current home, just behind a new luxurious hotel under construction at the Chroy Changva district is only temporary and that they would have to move again soon. (Photo by Damir Sagolj/Reuters)

Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)