This mythical creature is a combination of a fish and a centaur. It has the head, torso, and arms of a human, and the lower body of a fish. It is said to inhabit the depths of the sea, and is often depicted in ancient Greek
From Wikipedia
In late Classical Greek art, an ichthyocentaur is a centaurine sea being with the upper body of a human, the lower anterior half and forelegs of a horse, and the tailed posterior half of a fish.