When you and I take a deep breath, we pull air into our lungs. That’s because humans are mammals. But fish aren’t mammals. They usually don’t breathe air. They usually don’t have lungs. That’s what I ...

A collaborative team of scientists recently found that there is no physiological evidence supporting a leading theory -- which involves the surface area of fish gills -- as to why many fish species ...

The distribution and concentration of dissolved oxygen and water temperature in the oceans and freshwaters are usually far more influential in shaping the growth and reproduction of fish than the ...

Humans' outer ears may have evolved from the gills of prehistoric fish, a new study finds. Gene-editing experiments indicate that cartilage in fish gills migrated into the ear canal millions of years ...