With my 5 monos I been raising since 2" I have found this to be true also in the beginning. Cause I think by nature they like to chase there prey moving prey attracts them. But I have gotten mine to eat off the gravel now. Mine will eat cut shrimp off the gravel after they have swallowed what they ate that was sinking. My observation with feeders is when they swim fast to run away my PB attack them. But when the feeder doesn't run away unafraid of them they seem to leave it alone. This has been my observation.