A fish ( pl. : fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.

Fish are vertebrates (vertebrates have backbones) that live in water. They breathe using special organs called gills.

Fin fish like salmon have gills, are covered in scales, and reproduce by laying eggs. Eels, by contrast, have worm-like bodies and exceedingly slimy skin.