Well we used to be able to go to lake Erie and net these awesome emerald shiners but thats all banned now and I never use minners anyways. I'd say medium to small unless you have real whoppers down there that will hit the large ones. Index finger sized seems too large though in a minnow. I think you'd be better off with the little ones. 1-1.5 inches like Darryl said. Try hooking the little ones through the meat right behind the dorsal fin and use real small aberdeen fine wire red or chartreuse eagle claw hooks. Don't get the spine or guts. You'll get more hookups and great action with the minnows.