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)

Ary Borges feeds his tiger named Dan at his home in Maringa, Brazil, Thursday, September 26, 2013. Borges is in a legal battle with federal wildlife officials to keep his endangered animals from undergoing vasectomies and being taken away from him. He defends his right to breed the animals and says he gives them a better home than they might find elsewhere in Brazil. (Photo by Renata Brito/AP Photo)

A “jungle nymph” is measured during the annual weight-in ZSL London Zoo on August 21, 2014 in London, England. The height and mass of every animal in the zoo, of which there are over 16,000, is recorded and submitted to the Zoological Information Management System. This is combined with animal measurement data collected from over 800 zoos and aquariums in almost 80 countries, from which zoologists can compare information on thousands of endangered species. (Photo by Oli Scarff/Getty Images)

Snorkelers interact with a Florida Manatee inside of the Three Sisters Springs in Crystal River, Florida January 15, 2015. On winter days, Florida manatees flock by the hundreds to the balmy waters of Three Sisters Springs, drawing crowds of snorkelers and kayakers to the U.S. sanctuary, where people may swim with the endangered species. But as tolerant as the gentle, whiskered sea giants can be of the accidental kicks and splashes of delighted tourists, wild life regulators want to ban most canoes and paddle boards and create people-free zones to protect the wintering “sea cow”. Proposed limitations for this winter are awaiting approval by the U.S. Fish and Wildlife Service. (Photo by Scott Audette/Reuters)

A monarch butterfly rests on a visitor's hand at the Monarch Grove Sanctuary in Pacific Grove, California December 30, 2014. Monarch butterflies may warrant U.S. Endangered Species Act protection because of farm-related habitat loss blamed for sharp declines in cross-country migrations of the orange-and-black insects, the U.S. Fish and Wildlife Service said. (Photo by Michael Fiala/Reuters)

A picture taken on June 3, 2022 shows a unique albinos Galapagos giant tortoise baby, born on May 1, at the Tropicarium of Servion, western Switzerland. Albinos Galapagos tortoises have never been observed in captivity or in the nature. The Galapagos giant tortoises are strictly protected and are among the most endangered species among CITES-listed animals. (Photo by Fabrice Coffrini/AFP Photo)

A Thai Buddhist monk performs a religious rite blessing elephants and mahouts to mark the National Elephant Day at the Ayutthaya Elephant Palace and Royal Kraal in the world heritage city of Ayutthaya, Thailand, 13 March 2025. The National Elephant Day has been observed annually on 13 March since 1998 when it was established by the Thai government, in an effort to protect and conserve Thai elephants, who are part of the Asian elephant family classified as an endangered species. (Photo by Rungroj Yongrit/EPA)

A golden snub-nosed monkeys (Rhinopitheque de Roxelane) looks through its enclosure after quarantine during its presentation at the Beauval Zoopark in Saint-Aignan Central France, on May 7, 2025. ZooParc de Beauval (Loir-et-Cher) welcomed three golden snub-nosed monkeys on April 3, 2025, an endangered species from China, as part of a conservation program, becoming the first zoo outside Asia to house these long-haired, red-furred primates with bluish faces. (Photo by Guillaume Souvant/AFP Photo)