Villagers from the Medio Jurua nature reserve of Brazil's Amazon rainforest arrive with their catch of pirarucus, the largest freshwater fish in South America, after a night of fishing in Manaria Lake, Carauari municipality, September 3, 2012. Catching the pirarucu, a fish that is sought after for its meat and is considered by biologists to be a living fossil, is only allowed once a year by Brazil's environmental protection agency. (Photo by Bruno Kelly/Reuters)

In this aerial view fishing boats are seen on the shore of the Lake Malawi at the Senga village on May 20, 2019 in Senga, Malawi. Hundreds of local traders gather each morning and afternoon at Senga, but fish populations are falling in Lake Malawi, Africa's third largest body of freshwater. (Photo by Gianluigi Guercia/AFP Photo)

In this image released on October 1, Russian model Irina Shayk is seen onstage during Rihanna's Savage X Fenty Show Vol. 2 presented by Amazon Prime Video at the Los Angeles Convention Center in Los Angeles, California; and broadcast on October 2, 2020. (Photo by Jerritt Clark/Getty Images for Savage X Fenty Show Vol. 2 Presented by Amazon Prime Video)

In this image released on October 2, Bella Hadid is seen backstage during Rihanna's Savage X Fenty Show Vol. 2 presented by Amazon Prime Video at the Los Angeles Convention Center in Los Angeles, California; and broadcast on October 2, 2020. (Photo by Jerritt Clark/Getty Images for Savage X Fenty Show Vol. 2 Presented by Amazon Prime Video)

In this image released on September 23, Madonna's daughter Lourdes “Lola” Leon is seen during Rihanna's Savage X Fenty Show Vol. 3 presented by Amazon Prime Video at The Westin Bonaventure Hotel & Suites in Los Angeles, California; and broadcast on September 24, 2021. (Photo by Kevin Mazur/Getty Images for Rihanna's Savage X Fenty Show Vol. 3 Presented by Amazon Prime Video)

“7584 Fish”. On a windy day right after a Cyclone passed the far northern Great Barrier Reef i took some friends out to the reef. Never before i saw that many glass fish on this particular coral “bommie”. Just when i setup my camera, this Napoleon Wrasse swam right through the school of fish building a living frame. Photo location: Cairns, Great Barrier Reef, Flynn Reef, Australia. (Photo and caption by Christian Miller/National Geographic Photo Contest)

These unique photos capture the moment a boy has his teeth picked clean by amazing underwater shrimp. These fascinating creatures spend their lives diving inside the mouths of fish to remove the parasites that lurk there. Russell Laman imitated the behaviour of the surrounding fish swarm to entice the cleaner shrimp into his mouth whilst snorkelling with his father Tim Laman in Bali, Indonesia. The 13-year-old queued with the waiting fish and then opened his mouth when the shrimps came near. (Photo by Tim Laman/Caters News)

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)