Merpeople are aquatic humanoids in Ugly Americans. A merperson is a humanoid creature with head, torso and limbs similar to a human, however, their heads are fish-like and they have green scaly skin, webbed digits, and fin-like ears.
Note that they are different from mermaids. The two are different aquatic species. Merpeople do not have fish tails for their lower bodies as mermaids do.