With that much water available is there any way that you could enlarge that pond?
1/2 an acre can be tough to manage because it can become over populated in a hurry if you don't stay on top of things.
Fathead Minnows
Golden Shiners
Lake Chubsuckers
Mississippi Grass Shrimp
Papershell Crayfish
Those are a good start to your food chain with, no matter what else you end up stocking.
If your pond stays cold you could consider smallmouth instead of largemouth. In which case, you would want to stay away from bluegill. Something that reproduces a little less voraciously would be a better choice.
