Stock Photo - For anglers the brown trout Salmo trutta is a very popular fish which as a wiley but aggressive predator always presents a challenge The specimen shown is relatively large and has been introduced to a flooded quarry in the north of England Younger fish feed on invertebrates but large older individuals will also take small fish The latter are often called ferrox trout and may develop a hooked lower jaw Prefers the cool clean waters typical of mountainous regions but is more tolerant of warm water than other members of the salmon family To 700 mm From Iceland throughout Europe to parts of western Asia Cosmopolitan by introduction including Australia, New Zealand, India, E Africa, S Africa, N America and S America