Palaemon

Palaemon and his legion of sharks fought alongside Poseidon during the Second Olympian War. Poseidon sent the God of Dolphins, Delphin to send him to the western front.

Debated Species
It is implied that Palaemon is the God of Sharks, as he has a "legion of sharks". The Greeks also thought of him as the god of harbors. But he may also be the God of Sharks and Harbors.