The general consensus among biologists & pond managers is : don't put Crappie in less than 50 acres of water, and don't put White Crappie in small water bodies, at all. They're too prolific & will readily stunt.
The Shad being in there is also a problem, because the larger predatory fish will eat them ... rather than the smaller panfish.
That's what I've heard, anyway. And it held true on a small lake around here for many, many years.