anything from a 15-25 gram, long/tall slip float would be good for up to 6 maybe 7 inch minnows. just make sure you have a correct rig set up and location down.. ideally you want to fish either just above or beside a weed bed with a drop off from about 8-15 feet.
-rubber stopper above the float, figure out your depth.
-good sized split shot weight(s) to bring it down slightly above the swivel.
-swivel to leader to hook.
this is pretty much a standard set up and one i always use.. i'll even toss it on at night for walleye with a glow stick if i get tired of casting.