No they will fight. Try flatworm exit. It actually works really well. Just plan to have a water change ready since you need to suck out all the dying flatworms. Just remember for every 1 you see there are 10 more you don't
20 Gallon SPS reef
29 Gallon FW "fat catfish" tank
20 Gallon Long Dart Frogs "Zig" and "Zag"