I have a yearling Southern Black-Knobbed & two 6MO Mississippi Map Turtles in a 55gal tank with fish. I have 1 rubber-lipped pleco, 1 dalmation molly, 2 fancy guppies and 2 platies with them. I also have one 2in crayfish, several ghost shrimp, and 1 small freshwater mussel with them. The turtles will catch and eat a fish once in a while, but are usually to slow to catch them. The key is to buy cheap hardy fish that please your eyes, accepting that they may get eaten when you put them in. The ghost shrimp do well because they're good at avoiding the turtle's attention. The crayfish is perfectly sized. He's too big to be eaten, but too small to attack the turtles. The dalmation molly is the 'Rocky Balboa" survivor of the tank. She's been in there since the start, about three or four months ago. I did see a turtle get ahold of her by her tail fin once, but she got away and lived to swim another day. Avoid fish with overly big fins that may give a turtle and extra chance of catching them. As a side note, I plan on trying dwarf gourami and more platies in the tank. Going to try to breed the platies for turtle food. Getting rid of the fancy guppies because they disappear against my backdrop of browns and greens in my tank. The orange, yellow, and black platies really stand out in my tank and give it color.