Lake Pamvotis has been around for millions of years and is one of the oldest lakes in the world (second-oldest in Europe). It remained hospitable during the Ice Age and many animals from northern Europe sought shelter here. Today the lake is a sensitive ecosystem and a designated site of the NATURA 2000 network. It is home to 170 species of birds (including the extremely rare ferruginous duck), 9 species of amphibians (such as the northern crested newt and the yellow-bellied toad), 24 species of reptiles, two species of tortoises (the European pond turtle and Hermann's tortoise). The fish population includes both native and imported species; notable among them are the eel, the Albanian barbel, and tsima (Pelasgus epiroticus), a species of freshwater minnow that is critically endangered.