Legendary Fishermen

With the new wave of Kairyu-Shin support, the Legendary Fisherman just got a whole lot better.

Note: all the level 5 monsters can be normal summoned without tribute if A Legendary Ocean is on the field. It also enables most of those monsters' effects. Therefore you should get A Legendary Ocean out as soon as possible, though you'll have to keep track of monster levels if you want to go into Xyz plays.

You could also slot in Kyouto Waterfront for Gameciel's insane omni-negate effect (bring him out with Electric Jellyfish). If you go this route, Sea Stealth II would be your Umi source.