I think the only thing that would make me kill off the pond is the crappie. I think the other species could be controlled through intensive fishing and removal. I say that because a winter fish kill a few years back removed a bunch of BG and LMB from my 1 acre pond, and selective fishing has both species coming back fine with nice size (along with RES). Maybe someone with black crappie can lend some advice on this species in a 3 acre pond. Would a non-breeding apex predator (pike family or HSB) perhaps work to lower the number of intermediate size fish?