Fishmen are one of two humanoid species that inhabit and rule the seas (the other being the merfolk). In terms of leadership, King Neptune is the king of Fishman Island. Fisher Tiger, Jimbei, and Arlong were said to have the highest respect amongst their people. They are classified as Type C creatures, "Big Savage".
Fishmen are more fish-like than merfolk, usually looking like a combination between a man and a fish or other aquatic creature, such as an octopus, manta ray, or sawshark; however, they still have legs (in fact, Decken has four). They also have gills between their shoulders and necks, sometimes covered by their clothing, as well as often having webbed hands. Depending on species, they may have multiple limbs (mainly extra arms).