Well buddy...the first thing you need to do is to provide plenty of cover for their food.
A Crappie pond is a Bear to take care of and manage...BUT, IT CAN BE DONE!
Crappie are voracious predators...the reason they stunt, is they eat up all of the available forage and then are left to mainly eating insects and their own fry after they spawn.
First you need to put as much "Lay-down" cover as possible in the shallows, between the bank and the drop-off. You can use branches, 'boo, shrubs, Christmas trees, stacked UNTREATED wooden pallets, etc.! If you need to stock minnows, etc., now is the time to do it.
THE WHOLE REASON THAT THIS WILL WORK, IS THAT YOU PROVIDE ENOUGH FOOD FOR THE CRAPPIE TO GROW, AND THEN YOU HARVEST PLENTY OF CRAPPIE TO KEEP THE BALANCE!
Then start adding cover for the Crappie...limbs in buckets, "boo in buckets, milk crate stumps, pvc in buckets, etc! There are plenty of pictures in other threads on this forum...or when you're ready we can post more!
Good Fishing
Brent