Gambusia (mosquitofish) aren't really baitfish, but it's one example. A similar one would be wild sailfin mollies. The best FW baitfish in Florida (from my experience) are shad and golden shiners. The shad won't survive being caught in a net, so you can scratch that off the list. Golden shiners are great; they are probably the best bass bait and they are similar to ditherfish like tinfoil barbs. However, they do get about 10". I have caught and kept them before with other natives. If you want to go smaller you could get some seminole killifish, golden topminnows, flagfish, or bluefin killifish.