Even who is approaching fly fishing for the first times may have noticed that there are some beautiful places where trout are so plenty that in some pools there is more fish than people in a crowded rave party. Obviously, they are not native fish. They are stocked fish, fresh from the hatchery pool, grown up with fodder to a remarkable size and then set into the river, just to please fishermen. This fish is unfit to survive in a wild environment, often carrying illnesses and in almost all cases it will not spawn a single time (there are plenty of studies showing how grown up stocked fish is only seldom able to reproduce). So why are these 'artificial paradises' ruled on a catch and release base? They are managed following a pure economical interest, without any consideration for the ecosystem.