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) Europe.

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

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

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) Sava river, Slovenia, 2005

Barry Bland / Rainbow Trout {Salmo gairdneri} Fly Fishing on the Clutha River, Wanaka, New Zealand. Model Released.

Kim Taylor / Rainbow trout, deformed fry - siamese twins - caused by egg damage {Salmo gairdneri}

Kim Taylor / Rainbow trout {Salmo gairdneri}

Kim Taylor / Rainbow trout hatching from egg {Salmo gairdneri} sequence 2/4

Michael Durham / Rainbow Trout (Oncorhynchus mykiss) pair underwater in Utah, a popular game fish native to coastal streams of the western US and introduced into the eastern US and worldwide

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

Norbert Wu / Rainbow Trout (Oncorhynchus mykiss) pair, side view, western United States

Charlie Summers / Rainbow trout (Oncorhynchus mykiss) in green turbid waters,Gunnison River, Colorado, USA, April.

Charlie Summers / Rainbow trout (Oncorhynchus mykiss) in cold turbid water, Gunnison River, Colorado, USA, April.

Charlie Summers / Rainbow trout (Oncorhynchus mykiss) in cold turbid water, Gunnison River, Colorado, USA, April.

John Waters / Rainbow trout (Oncorhynchus mykiss) and Brown trout (Salmo trutta) swimming in the River Kennet, Berkshire, England, UK, March.

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

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

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

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

Cheryl-Samantha Owen / Rainbow trout (Oncorhynchus mykiss) caught in net as part of an eradication program, Krom River, Cedarberg Mountains, Western Cape, South Africa. A species introduced to the Krom River for angling pur...

Cheryl-Samantha Owen / An employee from 'Cape Nature', a government conservation department, fishing for introduced Rainbow trout (Oncorhynchus mykiss) in an attempt to eradicate them from the Krom River, Cedarberg Mountain...

Pascal Kobeh / Rainbow trout / salmon trout (Oncorhynchus mykiss) migrating up river to spawn, Alaska, USA.

Brandon Cole / Rainbow Trout (Oncorhynchus mykiss) alevin about 2 weeks old, still being nourished by yolk sac. Washington, USA.

Jussi Murtosaari / Rainbow trout (Oncorhynchus mykiss) invasive species, native to cold-water tributaries of Pacific Ocean in Asia and North America. Taken in aquarium, central Finland, May.

Alex Mustard / RF- Rainbow trout (Oncorhynchus mykiss) under trees, Capernwray Lake, Lake District, England, UK. (This image may be licensed either as rights managed or royalty free.)

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Rainbow Trout (Oncorhynchus mykiss), on spawning ground. Male approaching female to spawn. Lichtensteiner Binnenkanal, tributary of the Rhine River, Lichtenstein, January.

Michel Roggo / Dead Rainbow trout (Oncorhynchus mykiss). Tolminka river, tributary of the Soca river, Julian alps, Slovenia, September.

Michel Roggo / Dead Rainbow trout (Oncorhynchus mykiss). Tolminka river, tributary of the Soca river, Julian alps, Slovenia, September.

Andy Trowbridge / Fly fisherman drifting a fly pass a rainbow trout (Oncorhynchus mykiss) in a gin clear 'backcountry' stream, North Canterbury, Selwyn District, South Island, New Zealand. February, 2006.

Peter Cairns / 2020VISION / Osprey (Pandion haliaetus) in flight with caught rainbow trout. Cairngorms National Park, Scotland, May.

Alex Mustard / 2020VISION / RF- Rainbow trout (Oncorhynchus mykiss) in lake, Capernwray, Lancashire, UK, July. Did you know? Rainbow trout were indigenous only to Alaska and east Asia, but have been introduced worldwide as a pop...

Alex Mustard / 2020VISION / Rainbow trout (Oncorhynchus mykiss) portrait, Capernwray, Lancashire, UK, July

Linda Pitkin / 2020VISION / Brown Trout (Salmo trutta) and Rainbow Trout (Oncorhynchus mykiss) in disused quarry, Jackdaw Quarry, Capernwray, Carnforth, Lancashire, UK, August

Graham Eaton / Rainbow Trout shoal (Oncorhynchus mykiss) in a lake, Lancashire, UK, February

Graham Eaton / Rainbow Trout (Oncorhynchus mykiss) in a lake, Lancashire, England, UK, February.

Wild Wonders of Europe / Roggo / Rainbow trout (Oncorhynchus mykiss) in a mountain lake with fallen tree trunks in water, Berner Oberland, Swiss Alps, Switzerland, April 2009