A performer entertains the crowd during a rally in support of the leader of the Cameroonian opposition party Movement for the Rebirth of Cameroon (MRC) in Yaounde, on September 30, 2018, prior to the upcoming October 7, presidential elections. (Photo by Marco Longari/AFP Photo)

Astronauts Harrison Schmitt (left) and Eugene Andrew Cernan practice taking geological samples at the Kennedy Space Center in Florida, in preparation for NASA's scheduled Apollo 17 lunar landing mission, on August 28, 1972. Schmitt is the Lunar Module Pilot and Cernan is the mission's Commander. They are training for their period of EVA (extravehicular activity) on the Moon. (Photo by Space Frontiers/Getty Images)

People perform Chinese Lion dance in Chinatown during the Chinese Lunar New Year in Lima, Peru on February 5, 2019. (Photo by Guadalupe Pardo/Reuters)

A physically disabled fox walks with its walking wheels wheelchair, developed by an animal lover by Van Yuzuncu Yil University Wildlife Conservation and Rehabilitation Center, after the fox found wounded in the urban countryside in Van, Turkey on December 05, 2020. The fox also received a physical treatment at the center. (Photo by Ozkan Bilgin/Anadolu Agency via Getty Images)

Students from Cambridge University make their way home after celebrating the end of the academic year at a May Ball in Trinity College on Tuesday, June 21, 2022. The first official May Ball in Trinity College's grounds was held in 1866 with the tradition quickly spreading to the other colleges. (Photo by Joe Giddens/PA Images via Getty Images)

People watch a brig with scarlet sails floating on the Neva River during the Scarlet Sails festivities marking school graduation in St. Petersburg, Russia, early Saturday, June 25, 2022. (Photo by Dmitri Lovetsky/AP Photo)

A dog sits in a plastic basin filled with water in Taipei, Taiwan, 05 May 2018. Betel nut seller Mr Luo, the dog's owner, said he puts his dog Ah Dai (Stupid Guy) in the water-filled basin whenever the weather get hot. Luo has a dozen pairs of glasses for Ah Dai, so the dog wears different glasses every day and many tourists take photos of Ah Dai. (Photo by David Chang/EPA/EFE)

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)