Magikarp is a pokemon from the original 150. He is known as the most worthless and easy-to-find pokemon in most of the games. The only reason you keep him is that his evolution is the most surprisingly change ever. Which is by far worth it in my opinion.
It's Japanese name is コイキング (Koikingu) which is based on the English word "King" and the Japanese word 鯉 (Koi) which means "carp".