Hippocampus

Hippocampi were aquatic, horse-like creatures. They had the body of a horse, a scaly fish's tail, and fins instead of hooves or a mane. Their fore part was also covered with very thin fins. They were good racers and good mounts.

Ecology
Being wild and willing to keep their free spirit, hippocampi were not easily tamed. They could be trained to carry and fight with a rider. Being good creatures they would more commonly serve good causes.

Mount
They served as a favored steed for sea elves and tritons and could even be the special mount of an aquatic paladin.