What are some other animals I can "safely" put in with carnivorous turtles?

I can’t find any straight answers as to what fish/other marine animals I can put in the tank with my turtles (besides “other turtles). I realise that when it comes to living creatures there is a significant chance of something going wrong but I want to know what generally works. We’re not talking Snappers here; I realise nothing lives together with a snapper. So far I have a bunch of yellow cichlids and one rosy red in a 55 gallon tank with my Painted and RES turtles and they can’t catch them. So what else lives in fresh, warm water that can’t turtles catch that won’t fight with the cichlids. One idea I already got was certain species of perch.