My belief is that if natural predators were not raised with feeder fish, they may lose their instinct to eat small fish. I have one tank housed with an 11-inch Frontosa with 1 to 2 inch lamprologus species, and the small lamprologus swim casually in front of the Frontosa big mouth with no fear. I even went away for 2 to 3 weeks vacation each year without feeding my tank and I didn't lose any fish to predation.
I used to own large Jack Dempsey from baby to adult and never fed him with feeder fish. Finally, I traded the fish with a LFS and the people there tried to feed him with guppies and goldfish. He just let the feeders swim in front of his face and showed no interest at all. He ate only pellet food.
I used to own large Jack Dempsey from baby to adult and never fed him with feeder fish. Finally, I traded the fish with a LFS and the people there tried to feed him with guppies and goldfish. He just let the feeders swim in front of his face and showed no interest at all. He ate only pellet food.