fish gills showing chloride cells

McCormick Laboratory
Environmental Physiology of Fish

University of Massachusetts, Amherst

A little about fish, physiology, and what we do:

Explore the links below to learn more about topics related to our work.

Smolt Biology

One of the most well-known characteristics of Atlantic salmon is their migratory life cycle which takes them from freshwater streams to the ocean, eventually to return to as adults to spawn in the place where they were born. This strategy, known as anadromy, places complicated challenges on fishes as they move between wholly different aquatic environments. Click here for a brief description of the anadromous physiology of Atlantic salmon.


One of the fundamental structures with which fishes regulate their internal ions and maintain osmotic homeostasis are ionocytes (also known as chloride cells and mitonchondrion-rich cells), located in the gills. These cells are critical for the uptake of ions in freshwater and the excretion of ions in seawater. To help explain the complicated function of these cells, developed this flash model contrasting chloride cell function in fresh and salt water. The illustration may also be downloaded as a powerpoint slide, for use with proper attribution citing the author.