One of the rarest fish in the country is slowly swimming back from the brink of extinction after being spotted in a California river for the first time in 10 years. The Southern California steelhead ...

Nishikigoi, better known as koi fish, are a well-known variety of the common carp. They are bright red and white and revered for their vibrance and grace. Even other animals, including their predators ...

The fish was found at 200 to 2,000 meters below the surface. At least 16 types of recently discovered deep-sea fish are among the darkest creatures ever found, according to a study published Thursday.

Humans' outer ears may have evolved from the gills of prehistoric fish, a new study finds. Gene-editing experiments indicate ...