World’s Freshwater Fish in Crisis

E360 Digest

March 24, 2026

Over the last half century, populations of fish migrating through the world’s rivers have dropped by 81 percent, according to a stark new U.N. report. 

Hundreds of species of fish, which together sustain hundreds of millions of people, are imperiled by warming, pollution, dams, and intensive fishing, according to the report, launched at a U.N. meeting on migratory wildlife now underway in Brazil. As threats mount, populations of freshwater animals are declining faster than populations of animals on land or sea.

With more than 250 rivers and lakes worldwide crossing international borders, conservationists say that countries must work together to protect imperiled fish. “Rivers don’t recognize borders — and neither do the fish that depend on them,” said coauthor Michele Thieme, deputy lead of freshwater for World Wildlife Fund U.S. 

The dorado catfish of the Amazon basin offers a prime example. A bottom dweller that grows to more than six feet long, the dorado catfish undertakes the longest migration of any freshwater fish in the world. It travels 7,000 miles over the course of its life, from its spawning grounds in the Peruvian Andes to its feeding grounds at the mouth of the Amazon River in Brazil, and back. Increasingly, it is threatened by dams, mining, and the clearing of forest along the course of its epic migration.

Currently, just 24 species of freshwater fish are listed under the U.N. Convention on Migratory Species as needing international protection. The new report finds another 325 species are candidates for such protection. Among the river basins at particular risk are the Amazon, the Danube in Europe, the Nile in Africa, the Ganges in India, and the Mekong in Southeast Asia. 

Said Thieme, “The crisis unfolding beneath our waterways is far more severe than most people realize, and we are running out of time.”