Many years ago, I drained and killed off the fish in a pond of about 3/4 acre. Let it fill back up a bit and stocked it with roses red fathead minnows. Before long, you could drive by on 4 wheeler and the pond seemed full of them. Then I started seeing fewer of them and before long none. Somehow, green sunfish had gotten into the pond. Within a relatively short time, they had wiped out the fathead. I added about 20 smallmouth bass. Still catch a smallmouth occasionally but none ever got very big. Still just full of green sunfish. Need to drain it again.
How did the pond get re-filled?
I think you need to determine the source of the GSF before you go to that much effort again. Perhaps there was a tiny bit of water left when you drained and you did NOT rotenone?
I would like to hear more, because reports like yours a fairly common on Pond Boss.
