The European flounder can also be found in estuaries where it is tolerant of low salinity levels and, unlike other species of Pleuronectidae, it often spends part of its life cycle in freshwater and regularly makes its way into rivers. In the British Isles, it has been found as far inland as Montgomeryshire on the River Severn, Dinas Mawddwy on the River Dovey and Garstang on the River Wyre. Unlike the Atlantic salmon, it feeds in the rivers and makes its way out to sea again before spawning.
