Ichthyocentaurs are the aquatic half-brothers of the centaurs, commonly known as 'fish centaurs'. They had the upper body of a man, the lower front of a horse, and the tail of a fish. Also, they wore lobster-claw horns. They were half-brothers of the wise centaur Chiron and the sons of Poseidon and the sea goddess Amphitrite.

These sea-centaurs were thought to be peaceful water-dwelling creatures; they tend to hold great value for their family and friends. Most of the time they are able to get along with other water-dwelling races. Because this type of race is still related to the wild nature of their centaur cousins, some of them still elicit harsh behavior, although not as much as the centaurs. The Ichthyocentaurs tend to roam in milder parties as opposed to more aggressive centaur parties. The ichthyocentaurs' relationship with the nymphs allowed them to live for centuries, having them tend to be aware of many situations in the sea.

The Ichthyocentaurs also have the ability to both breathe underwater and swim with great speed. They also have more physical stamina than any of the other aquatic races. Other abilities include being able to communicate underwater with several races that live there.

The two best-known ichthyocentaurs from Greek mythology were Bythos (Sea-Depths) and Aphros (Sea-Foam). Their parents were the Titan Cronus and Nymph Philyra. These two were half-brothers of Chiron the centaur, and were regarded as wise teachers, much like Chiron himself.