This response is targeted more for Greg and Bruce but hopefully it will help laurelew.

Could the combination of too many BG (and susequent fish squeezings), lack of a predator, 200 lbs of lime, supplimental feeding (amount not stated) and high temps result in the pond soup that has led to some fish die-off?? I understand no one wants to see their fish floating but would you be concerned with the number of dead fish these folks have noticed over the past few months. Like Bob has stated in the past, mother nature will fix the problem.

As for the advice from the hatchery, my thoughts side with Theo on the stocking of the number of BG. Although no size is stated, 300 sounds a bit on the high side for a 0.25 acre pond. Without any data from the water test (especially DO), I would question the advice on the surface aerator.