John Waters / Small group of Rainbow trout (Oncorhynchus mykiss) swimming in the River Kennet, Berkshire, England, UK, March.

Alex Mustard,Alex Mustard / Rainbow trout (Oncorhynchus mykiss) under trees, Capernwray Lake, Lake District, England, UK.

Andy Trowbridge / Underwater view of rainbow trout (Oncorhynchus mykiss) being released by a fly fisherman in a small spring fed stream, North Canterbury, South Island, New Zealand. December, 2011.

Michel Roggo / Underwater landscape in mountain lake with Rainbow trout, Berner Oberland, Swiss Alps, Switzerland, March

Michel Roggo / Underwater landscape with Rainbow trout under ice in alpine lake, Canton of Berne, Switzerland, January

Michel Roggo / Rainbow trout (Salmo gairdneri / Oncorhynchus mykiss) Sava river, Slovenia, 2005

Michel Roggo / Rainbow trout (Salmo gairdneri / Oncorhynchus mykiss) in pool of the Lepena river, Slovenia 2006

Michel Roggo / Rainbow trout (Salmo gairdneri / Oncorhynchus mykiss) in pool of the Lepena river, Slovenia 2006

Michel Roggo / Rainbow trout (Salmo gairdneri / Oncorhynchus mykiss) eggs in hatchery, Switzerland, Captive

Michel Roggo / Rainbow trout (Salmo gairdneri / Oncorhynchus mykiss) Europe.

Michel Roggo / Rainbow trout alevins (Salmo gairdneri / Oncorhynchus mykiss) hatchery, Switzerland, 2003

Tim Fitzharris / Rainbow Trout (Oncorhynchus mykiss) pair swimming underwater