The Brown Trout (Salmo trutta) is a European species of salmonid fish, which consists of two distinct forms. One of them is purely freshwater, referred to Salmo trutta morpha fario; another is known as the Sea Trout (S. trutta morpha trutta) that migrates to the oceans for much of its life and returns to fresh water only for spawning. Here you can find some facts about the Brown Trout.
However, this fish species is also able to adapt to living in caves. In the UK, several populations of cave-dwelling Brown Trout have been found. Graham Proudlove, an Honorary Curatorial Associate at the Manchester Museum, presents a story of this unusual “cave” fish (see below).