The quality of the waters of the Madriu-Perafita-Claror valley means that there is a great variety of animals that inhabit the aquatic environments and that are threatened by the fragility of their habitat. Thus, all the amphibian species present in the valley are included in Annex II of the Bern Convention, which means that they are strictly protected species whose habitat is also protected by prohibiting the intentional deterioration or destruction of their breeding sites or resting areas.

In the clean waters of wetlands, rivers and streams we find the Pyrenean newt ( Calotriton asper ), a Pyrenean endemic threatened in our country due to habitat loss. The salamander ( Salamandra salamandra ), the common frog ( Rana temporaria ), and the common toad ( Bufo bufo ) also live in these humid environments.

As for fish (Actino, we can find, apart from the common trout ( Salmo trutta fario ), which is the only native species and present in most rivers and ponds, the rainbow trout ( Onchorhynchus mykiss ), the brook salmon ( Salvelinus fontinalis ), and the red barb ( Phoxinus phoxinus ).