I'm concurring with CJBS2003 as the fatheads just don't provide a large enough size for the larger fish. One of the things that promotes large healthy fish is size groupings of forage fish to fit their gape as they become larger with the lowest amount of energy consumed. Feeding on fathead minnows for a 1.5 pound crappie or a 5 lb. bass is like us eating food the size of peppercorns one at a time.
Seems like a lot of trouble when it could be done with a larger forage fish.