Unlike tropical waters, temperate waters become cold during part of the year. Fish that live in such waters must adjust their living habits to changes in water temperature. For example, in lakes that freeze over during winter, most fish move down to warmer water near the bottom and remain there until spring. The fish pictured here live in temperate lakes, rivers, and streams of North America. Many alewives, coho salmon, rainbow trout, and white sturgeon live in salt water but swim into fresh water to lay their eggs.
American eels live in fresh water but swim to the ocean to lay their eggs.