Sea horse

The sea horse (formatted as the seahorse prior to ) is a sea fish in the introduced in.

Donating to the museum
Upon donating to the museum, Blathers will say the following:

In
After being accepted by Blathers, the seahorse can be found bobbing around in the sea tank of the aquarium.

In
It can be found in the bottom-right tank with the other small, sea fish like the clownfish and sea butterfly.

In
Upon donation, the information board outside the tank that houses the seahorse says:

Fishing Tourney
During a Fishing Tourney, when given a sea horse, Chip will say the following dialogue.

Real-world information
The males carry the eggs in a brood poach located under the tail. The females lay their eggs into the pouch, and the male carries them around until they hatch. It is a harmless fish, popular in private and public aquariums.