I have tried a few diff fish, mandering, leopard wrasse, melanarus with no luck. The issues I think is there are better things too eat so until you starve them they don't seem to want to eat flatworms. I usually end up with all pods gone and flatworms. i have tried the nutrient export but they are so low on food cahin hard to get rid of them. I have a low nut syst not ULNS still have flatworms (0- N & 0- P).