My pond is now three years old and I have caught about 75 Bullheads is three years. I am sure my problem came from the help of some miscreant who is jealous of my great 12 acre pond! They arrived on site full grown, so it would have been noticable to the bird if one was hanging on its foot!! I have only caught three this whole year and have never seen a small one. I think that by fishing near the food and throwing all of them out, I have finally eliminated them.