>>27730792Oh, right, there's one more really huge reason:
-Magikarp is an extremely important fish to recreational and sports fishermen. Magikarp may not have much of a following in the Pokemon battling scene, but there are a LOT of people in the pokemon world who are "Magikarp Fishing Otakus" (?). This makes sense though since Magikarp has been seen to come in a WIDE variety of sizes and it probably fights like a fucking bastard on the line- zipping, yanking and pulling all over the place.
Due to this success as a Sports Pokemon Fish it's undoubtedly that a lot of the success Magikarp has seen is thanks to people introducing them into ponds, rivers and artificial lakes and irrigation channels where they wouldn't naturally exists so they could fish for them.
The official japanese website even went ahead and did a little piece of Magikarp-love within their little pokemon world and you can check it out over here:
http://www.pokemon.jp/special/koiking_love/song/It's a shame it won't be translated though since I'm pretty sure they'd done this with other pokemon too and I can't help like I'm being left out on some prime world-building material.