This is what I would try if it were my pond in your location. Since your pond is small, I would for now and at least the next few years stay with the tilapia. Tilapia feed low on the food chain similar to gizard shad and provide numerous forage fish for predators. This way you have a fish that will not easily cause you too many problems due to geting too large and too abundant and taking up too much "space" or biomass in your pond. Your diversity in forage fish seems good to me and should be able to supply adequate forage fish for your bass if the bass do not become over abundant or out of balance. I see the tilapia a plus if you periodically loose them due to harsh winter. You can always restock if necessary. The cost should not be prohibitive. You will not have that option if you add gizzard shad which will be hard or practically impossible to remove unless you do complete fish eradiction. As your forage fish needs change or the tilapia are not meeting your expectations then rethink the use of g.shad. An added bonus is that larger tilapia are very good eating, at least the fresh ones are, that I get at a local food store. They are a very mild, good tasting and versatile fish for cooking. I don't think you will like eating g.shad too well no matter how you cook them.
