Horsea (Japanese: タッツー Tattu) is a Water-type Pokémon.

It evolves into Seadra starting at level 32, which evolves into Kingdra when traded holding a Dragon Scale.

Horsea is a small, blue, seahorse-like Pokémon with a single dorsal fin and a tightly curled tail. Its eyes are red and its ridged belly and dorsal fin are cream-colored. It has a long, tubular mouth and three spike-like projections on either side of its head.

It is highly adept in the water, using its dorsal fin to swim in any direction while facing forward. It can use its tail as both a balance and an anchor when caught in a strong current. In safer environments, it uses its tail to play with other members of its species. If Horsea senses danger, it sprays water or dense black ink from its mouth at its attacker. It can shoot ink more precisely at insects flying above the surface of the water. Horsea feeds on insects and moss gathered from rocks. It nests in coral reefs and islands throughout the ocean. Many Eggs are laid every year, and the young are raised by the male Horsea rather than the female.