New scientific research into European freshwater fishes showed that 200 of 522 species were under threat, while 12 had already vanished. The IUCN based in Gland in Switzerland claims fish face a greater level of risk than mammals or birds.
IUCN spokesman William Darwall said: "With 200 fish species in Europe facing a high risk of going extinct we must act now to avoid a tragedy."
Dried up rivers, caused by water abstraction in Mediterranean countries, irrigation and flood control measures had major impacts. Poor fish management and over-fishing were a problem too.
The worst hit areas were the lower reaches of the rivers Danube, Dniester and Dnieper (eastern Europe), Volga (Russia) and Ural (Kazakhstan) rivers, the Balkan peninsula and southwestern Spain.
"These species are an important part of our heritage and are critical to the freshwater ecosystems upon which we do depend, such as for water purification and flood control. Many of these species can be saved through relatively simple measures. All we need is the public and political will to make it happen," said Darwall.