I echo most of the comments above.
To summarize;
1) Fatheads are a complete waste of money.
2) Harvest intermediate size bass.
3) Protect your largest bluegill.
4) Golden shiners could fill an additional niche.
I have used rainbow trout as supplemental food. Here's what I like..you can feed a selected size of bass by choosing the size of trout. Cost is fairly reasonable, for a supplemental stocking with a singular purpose of giving specific sizes of fish a snack.
Over the years, my opinion of tilapia has begun to shift. Just five or six years ago, I believed tilapia were a band-aid. To an extent, I still believe that. They treat a symptom. If bass are losing weight, there's a 95% chance they are overcrowded for their natural food chain. By adding tilapia, you get a "quick fix" whereas, tilapia reproduce prolifically, providing lots of quick forage fish. But, at the same time, as tilapia are "overwhelming" a fishery, bluegill are also spawning. When you have lots of baby tilapia, the statistical odds of baby bluegill survival increases, simply because of sheer numbers. In the fall, when tilapia die, they do so slowly, allowing bass to gorge themselves. Then, going into the winter, you have a surviving crop of young of the year bluegill. At the same time, you have a larger standing crop of bass. When the tilapia are gone, you should stock again in the spring, to "prop up" the bass population...or harvest more intermediate size bass (which you should be doing anyway).
The answer is to cull bass, supplement the bluegill with other forage fish, feed your bluegill to enhance egg production and growth rates, monitor growth rates of bass to make sure what you are doing is working.
Here are a few additional things to do;
1) Monitor growth rates of bass
2) Diversify the forage fish which can reproduce successfully...threadfins, tilapia, golden shiners.
3) If you wish to supplement forage, consider rainbow trout and crawfish.
