I've often thought about that mainly the BG. I've only got 50 HSB assuming all stocked are still alive.. This past summer I discovered and influx of bull head that found there way into the pond as well. These might also be competing for food..Ive trapped and fished hundreds of them out to where they seem to be less abundant. With my overall stocking numers as low as they are I wouldn't think there is a big shortage of food. I put a lot of FHM in.