Michel Roggo / Perch (Perca fluviatilis). Juktan river, tributary of Umeälven river, Lapland, Sweden, July.

Michel Roggo / Grayling (Thymallus thymallus) on spawning ground. Lac de Fenetre, alpine lake, 2456 m above sea level, Canton of Valais, Switzerland, June.

Michel Roggo / Grayling (Thymallus thymallus) on spawning ground. Lac de Fenetre, alpine lake, 2456 m above sea level, Canton of Valais, Switzerland, June.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration; males surrounding a female. Adams River, British Columbia, Canada, October.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) on spawning migration. Adams River, British Columbia, Canada, October.

Michel Roggo / Atlantic Salmon (Salmo salar) in pool on upstream spawning migration. Quebec, Canada, August.

Michel Roggo / Atlantic Salmon (Salmo salar) male, captive in fish-farm. France.

Michel Roggo / Butterfly peacock bass (Cichla ocellaris) in flooded forest, Rio Tabajos, Amazon, Brazil.

Michel Roggo / Rio Negro flooded during rainy season, Amazon, Brazil, 1993.

Michel Roggo / Sunset at Rio Tabajos, near Santarem, Para, Brazil, 1994.

Michel Roggo / Karst spring where water bubbles up from subterranean source, Julian Alps, Slovenia, June 2008

Michel Roggo / Banded cichlid (Heros severus) in flooded forest. Rio Tabajos, Amazon, Brazil.

Michel Roggo / Matrincha (Brycon sp.) in flooded forest, waiting on surface for insects. Rio Tabajos, Amazon, Brazil.

Michel Roggo / Yellow-spotted river turtle (Podocnemis unifilis), Los Lagos, Beni, Bolivia, October.

Michel Roggo / Backwaters of the Rio Mamore with meanders and oxbow lake, Beni, Bolivia, January 2001.

Michel Roggo / Spectacled caiman (Caiman crocodylus) at water surface. Beni, Bolivia, October.

Michel Roggo / Uaru / Triangle cichlid (Uaru amphiacanthoides) in flooded forest, Rio Tabajos, Amazon, Brazil.

Michel Roggo / Three-barred / speckled peacock bass (Cichla temensis) entering flooded forest to spawn. Tributary Rio Tabajos, Para, Brazil.

Michel Roggo / Aracu (Leporinus sp.) in flooded forest, Rio Tabajos, Amazon, Brazil.

Michel Roggo / Underwater landscape in chalk stream, Croatia, October

Michel Roggo / Underwater landscape in Spring creek, Saane river tributary, in winter, Gruyre, Fribourg, Switzerland. February

Michel Roggo / Water plants in underwater landscape in chalk stream, Croatia, October

Michel Roggo / Underwater landscape in Spring creek, Saane river tributary, in winter, Gruyre, Fribourg, Switzerland. February

Michel Roggo / Turbulent waters in Verzasca River, Tessin, Switzerland, October

Michel Roggo / Underwater landscape in Hongrin River with ice on the river bed and surface in winter. Fribourg, Gruyre, Switzerland, December

Michel Roggo / Underwater landscape in Spring creek, Saane river tributary, in winter, Gruyre, Fribourg, Switzerland. February

Michel Roggo / Underwater landscape with fallen trees, Soca river, Slovenia, June

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

Michel Roggo / Fallen tree trunks and shafts of light in spring creek, Croatia, May

Michel Roggo / Underwater landscape in mountain creek, Swiss Alps, Gruyre, Fribourg, Switzerland, December

Michel Roggo / Underwater landscape in Hongrin River, Saane river tributary, Canton of Fribourg, Switzerland, September

Michel Roggo / Underwater landscape looking up at bubbles and water lily in ice, Doubs River, France, February

Michel Roggo / Underwater landscape in peat pond, Fribourg, Switzerland, August

Michel Roggo / Underwater landscape in peat pond, Fribourg, Switzerland, August

Michel Roggo / Underwater landscape in Verzasca River, Ticino, Switzerland, September

Michel Roggo / Underwater landscape in mountain creek, Swiss Alps, Gruyre, Fribourg, Switzerland, January

Michel Roggo / Underwater landscape with water lily in peat pond, Fribourg, Switzerland, May

Michel Roggo / Underwater landscape beneath ice in Rhine river oxbow, Switzerland, February

Michel Roggo / Underwater landscape in Verzasca River, Ticino, Switzerland, September

Michel Roggo / Underwater landscape beneath ice, Doubs River, France, January

Michel Roggo / Underwater landscape with River water-crowfoot (Ranunculus fluitans) Rhine river, Switzerland, June

Michel Roggo / Underwater landscape in Sava river, Slovenia, September

Michel Roggo / Turbulent water in Verzasca river, Ticino, Switzerland, February

Michel Roggo / Underwater landscape in peat pond, Fribourg, Switzerland, May

Michel Roggo / Underwater landscape in Verzasca River, Ticino, Switzerland, September

Michel Roggo / Underwater landscape in mountain creek, Swiss Alps, Gruyre, Fribourg, Switzerland, December

Michel Roggo / Underwater landscape with water lilies, Juktan, Sweden, July

Michel Roggo / Underwater landscape in Verzasca River, Ticino, Switzerland, February

Michel Roggo / Underwater landscape beneath waterfall, Baca River, Slovenia, June

Michel Roggo / Underwater landscape in Verzasca River, Ticino, Switzerland, September

Michel Roggo / Underwater landscape beneath ice with trapped bubbles, Doubs River, France, February

Michel Roggo / Split level landscape in oxbow of the Aare river, Switzerland, September

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

Michel Roggo / Underwater landscape in spring creek, Croatia, May

Michel Roggo / Red-eye / Rudd (Scardinius erythrophthalmus) in forest pond close to Aare river, Switzerland, May

Michel Roggo / Underwater landscape beneath ice in Aare river tributary Spring Creek, Canton of Berne, Switzerland, January

Michel Roggo / Underwater landscape beneath ice in Aare river tributary, Canton of Berne, Switzerland, January

Michel Roggo / Underwater landscape in spring creek, Croatia, May

Michel Roggo / Underwater landscape in Aare river, Canton of Berne, Switzerland, January

Michel Roggo / Underwater landscape in spring creek, Croatia, May

Michel Roggo / Underwater landscape in spring creek, Croatia, May

Michel Roggo / Looking down on Boat in flooded Amazon rainforest, Rio Negro during rainy season, Brazil 1994

Michel Roggo / Rudd (Scardinius erythrophthalmus) Europe

Michel Roggo / Signal crayfish (Pacifastacus leniusculus) Europe, introduced from North America

Michel Roggo / Pumpkinseed fish (Lepomis gibbosus) Europe

Michel Roggo / Lake trout (Salmo trutta lacustris) morph of the Brown Trout, Europe

Michel Roggo / Carp (Cyprinus carpio) in forest pool close to the Aare River, Switzerland, 2005

Michel Roggo / Chubb (Leuciscus cephalus) under ice in frozen river, Aare river, Switzerland 2006

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) migrating upstream to spawn, Adams river, British Columbia, Canada 2006

Michel Roggo / Nase (Chondrostoma nasus) at spawning ground, Saane River tributary, Switzerland, 2006

Michel Roggo / Carp (Cyprinus carpio) Aare river, Switzerland, 2004

Michel Roggo / Pike (Esox lucius) hiding under aquatic vegetation, Doubs River, France, 2001

Michel Roggo / Rudd (Scardinius erythrophthalmus) close up of anal fin, Europe, Captive

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

Michel Roggo / Bullhead (Cottus gobio) Europe

Michel Roggo / Tench (Tinca tinca) on the surface of a turbid marsh pond, with Rudd (Scardinius erythrophthalmus) above, Fribourg, Switzerland, 2004

Michel Roggo / Rudd (Scardinius erythrophthalmus) at surface of peat pond, Fribourg, Switzerland 2006

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka) waiting in lake to enter the Adams river for migration upstream, British Columbia, Canada 2006

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

Michel Roggo / Goldfish (Carassius auratus) Europe

Michel Roggo / European Eel (Anguilla anguilla) juveniles migrating upstream, Rhine River, Switzerland, 1992

Michel Roggo / Nase (Chondrostoma nasus) male at spawning ground, Saane River, Switzerland, 2004

Michel Roggo / Lake trout (Salmo trutta lacustris) morph of Brown Trout, jumping up waterfall on migration to spawning ground, Lac de Neuchtel, Switzerland 2006

Michel Roggo / Marble trout (Salmo trutta marmorata) morph of the Brown Trout, at spawning ground, Tolminka river, Slovenia, 2005

Michel Roggo / Marble trout (Salmo trutta marmorata) morph of the Brown Trout, female at spawning ground, Tolminka river, Slovenia, 2005

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

Michel Roggo / Chum / Dog Salmon (Oncorhynchus keta) in resting pool on migration upstream to spawn, Weaver Creek, British Columbia, Canada, 1989

Michel Roggo / Roach (Rutilus rutilus) spawning behavior, tributary of the Lake of Seedorf, Fribourg, Switzerland 2006

Michel Roggo / Carp (Cyprinus carpio) in forest pool close to the Aare River, Switzerland, 1992

Michel Roggo / Minnow (Phoxinus phoxinus) in shallow water close to the shore, spawning time, Doubs river, France, 2005

Michel Roggo / Marble trout (Salmo trutta marmorata) morph of the Brown Trout, male and female at spawning ground, Tolminka river, Slovenia, 2005

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

Michel Roggo / Sockeye / Red Salmon (Oncorhynchus nerka), female digging to lay eggs on spawning ground, Adams river, British Columbia, Canada 2006