I keep a shoal of about 100 feeder guppies in with my RES, western painted, and african sideneck (Pelusios castaneus). The turtles love eating goldfish and rosy red minnows (both an occasional treat), but they don't bother with the guppies. Started with 4 guppies, and they just keep multiplying. There is also a lonely male platy and 4 zebra danios. I originally added 6 platies and 6 danios as feeders, but the sideneck got them. They seem to leave these guys alone now, preferring the bigger goldfish, minnows, and especially the chunks of pumpkin I've been giving them as of late.