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 fronts were covered with small scales, with larger scales at their rears. They were good racers and good mounts.

Uses
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.

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