FISH ATLASGLOBAL FISH ENCYCLOPEDIA

FISH SPECIES

Freshwater Fish

Freshwater fish spend all or part of their lives in rivers, lakes, streams and wetlands. The label describes an environment, not one branch of the fish family tree, so freshwater species include many unrelated shapes and lineages.

FISH ATLAS / FIELD GUIDEFreshwater FishIN THIS CHAPTER01 / Characteristics02 / Lifestyle03 / Species04 / Field notes
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01 / NATURAL HISTORY

Characteristics

Freshwater habitats contain far less salt than seawater and can change quickly with seasons, floods and drought. Fish living there use many different strategies, from streamlined bodies for current to barbels that help find food near the bottom.

  • 01River fish
  • 02Lake fish
  • 03Stream fish
Nannostomus marginatus 的物种图片
Freshwater Fish

02 / LIFESTYLE

Lifestyle

Life in freshwater follows the movement of water and food. Some fish hold position in a current and intercept drifting prey; others search plants or sediment for a meal. Changes in flow and water level can open feeding grounds or trigger movements toward spawning areas. These behaviors reflect how fish balance hydrodynamic energy expenditure against food intake.

OBSERVATION INDEX

  1. Holding position in a current
  2. Feeding among plants or sediment
  3. Movement with changing water levels

03 / SPECIES

Representative species

View all species

Discover representative species illustrating the ecological diversity, morphologies and adaptations of this group.

04 / FIELD NOTES

A closer look

What makes a fish freshwater?

It is recorded from inland waters with low salinity for all or part of its life cycle.

Are all freshwater fish closely related?

No. Freshwater is a habitat category that includes many separate evolutionary groups.

Can freshwater fish survive in seawater?

Most cannot; without physiological adaptations to excrete excess salt, their cells rapidly lose water through osmosis and dehydrate in hypertonic seawater.