you have to fish near the left of flabbar town you can also catch a whishcash wit a super rod on top of the waterfall in meteor falls
you can catch a barboach in Pokemon ruby by fishing on the bridge to the west of Fallarbor town wit ha good or super rod
safari zone (special item) you can transfer from sapphire or ruby.
The Before form of the Water and Ground type Whishcash is the small Water and Ground Barboach. Barboach is only avalible in Pokemon Diamond, Pearl, Emerald, Ruby, Sapphire and Platinum
Barboach evolves into Whiscash at Level 30 in Pokémon Ruby, Sapphire, FireRed, LeafGreen, Emerald, Diamond, Pearl and Platinum.
You can catch feebas everywhere and occasionally barboach i am unsure where to catch magicarp but there is a way
Lv30
You can go to Route 114, 115, 111, 120, Ever Grande City (Pokemon Center), probably by fishing and/or surfing. Hope you find it! -PF
barboach
Barboach
Barboach
At lv35, Barboach evolve into Whiscash...
barboach? http://pokemon.marriland.com/platinum/pokedex/barboach/ look at the bottom