It is often thought that there are multiple species of trout; brown, speckled, brook and river and so on. In fact they are all one, with the exception of the rainbow trout, and the differences in pattern are owing to environmental variations. The sea trout is a trout which spends a couple of seasons at sea, eating small crustaceans which make it a pink colour. They are all the same fish. The name simply comes from where it is caught or its appearance (which may be affected by its diet). It is coarser-fleshed than salmon.