I am definitely not a pro. I would not want to spend money to trade one problem for another. If I understand the problem, too many crappie in a 1/3 acre pond, nuking the pond is not an option and there are already LMB in the pond, I have no suggestions other than stocking a few FHC to clear it up over time and then hope I could get the FHC out.....???? Hopefully, a pro will offer a better suggestion than that!