How do you catch a Magikarp in emerald?

You have to go back to the sea where you found a lumineon. There are two seas you want to go to the one that is NOT Wailord Sea. You have to go the same place where you found lumineon which means you will need a couple of mantine to get you over the the place with all the fast rapids. Then you have to chase it around until you can catch up to it. I say you study where all the rapids are and then find a shortcut that will help you get the the sharpedo faster i say use the last rapid before you head to the very top of the place and then quickly get the next rapid before he gets to far ahead and keep trying to catch up to him because I did the same thing and I caught up to him. When you chase it around and capture it, it won't stay captured. You gotta find another own.Somewhere ELSE!

Somewhere else eh? Theres one in Sea of Wailord. If your going for look, i think theres only two sharpedos, but if your going for target clear, you can use a seadra or kingdra. Kingdra doesn't thrash as much.