Ingo Arndt / Amu-Darya Trout (Salmo trutta trutta) alevin hatching from egg, Europe

Ingo Arndt / Amu-Darya Trout (Salmo trutta trutta) egg with alevin already visible through egg-shell, Europe

Ingo Arndt / Brown Trout (Salmo trutta) alevins, Europe

Ingo Arndt / Brown Trout (Salmo trutta) alevin hatching from egg with full yolk sac, Europe

Jane Burton / Brown trout {Salmo trutta} one-week-old alevin on river gravel, captive, from Europe, life cycle sequence 8/14

Jane Burton / Brown trout {Salmo trutta} alevin hatching from eggs, captive, from Europe, life cycle sequence 3/14

Jane Burton / Brown trout {Salmo trutta} three/four-weeks-old alevin, captive, from Europe

Jane Burton / Brown trout {Salmo trutta} three/four-weeks-old alevin, captive, from Europe, life cycle sequence 11/14

Hiroya Minakuchi / Chum Salmon (Oncorhynchus keta) alevins, native to the Pacific Ocean

Hiroya Minakuchi / Chum Salmon (Oncorhynchus keta) alevins, native to the Pacific Ocean

Hiroya Minakuchi / Chum Salmon (Oncorhynchus keta) eggs and alevins, native to the Pacific Ocean

Michael Durham / Coho Salmon (Oncorhynchus kisutch) hatches from its egg, Washington