With what Pokemon can you breed a female Feebas in Diamond?

In Pokémon Diamond, you can breed a female Feebas with a male Pokémon from the same egg group. Feebas belongs to the Water 1 egg group, so you can breed it with any male Water-type Pokémon, such as a male Magikarp or a male Goldeen. The resulting eggs will have a chance to hatch into Feebas.