Smaller sunnies like a few orangespots or bluespots, darters, dace, banded topminnows, flagfish, highfin mollies, least killies or any native killies, pygmy sunfish...
Well in mine I have Guppies male and females, mollies, gourami blue and gold, pleco, thats about it but I have many in mine. And plus guppys are livebearers so I will have many more soon. Just make sure you have alot of hiding places for the babys.