If you never feed your predatory fish with live food, they will lose their instinct to eat small fish. My large predatory fish are all raised with pellets, and they do not eat small fish. Currently, I have a 10" Frontosa, 7" lepidiolamprologus elongatus, and a 7" Sciaenochromis fryeri predators that co exist peacefully with a school of 1.5" Diamond Tetra and Molly.