jsand and Jeff give sound advice.
It's not that crappie are bad for smaller bodies of water, it's just that they are unpredictable spawners and don't play well with other predators.
They can very quickly overpopulate and decimate smaller-sized forage. Without extremely careful management, they can become stunted and cause other predators to become stunted.
That being said, I think crappie would be great in pond-sized bodies of water in certain situations--again, with careful management. Our "crappie pond," when we're finished stocking, will have black crappie, HSB, FHs, TFS, and GSH. As long as we monitor crappie recruitment and adjust accordingly, I think crappie will work well even in a pond.
