I think your question is alittle to broad to answer. It depends on what you want out of your pond. answers will vary depending on what species of fish you prefer to manage for, the size pond you have, where it is located and so on. Stocking a pond with additional fish like treadfin shad will be great for bass fishing, but watch out if you want good bluegill fishing. Just because you have a bunch of different species of fish living in the pond does not mean its a good fishery. they all compete for the same food. A pond will only hold a certain amount of fish, this amount is called its carrying capacity. Here in Georgia the carrying capacity for an unfertilized pond is 100 pounds of fish per acre. you can stock it full of bluegill, let them overpopulate for 2 years, drain the pond and you will have 100 pounds of skinny, terrible looking bluegill. Then stock the same pond with proper rates of bass, bluegill and red ear. give them two years to grow in a balanced fish population. drian the pond and weigh all the fish and you will still have 100 pounds of fish, but this time they will be fat, healthy fish.
I say this so you will understand that if you stock additional fish into your pond you are not increasing to your forage base. whatever fish you add will be taking away food from other fish in the pond.
there are not many fish that will produce more forage than good old bluegill. I would not recommend "playing" scientist with your pond and stocking fish to see what happens. Unless you are willing to drain the pond, kill all fish and start over.
