We did stock grass carp at 10 per acre 2 yrs ago with no visible impact yet, but I'm told it takes 2-3 years to see any change. My concern is that we've had some heavy rains and some neighbors downstream from our spillway report seeing GC in the creek. We've also had at least 3 otters in our lake in the last couple years that have been persuaded to leave, but I don't know what they've done to our GC population. Our largest predators are LMB and a few big CC. The GC were 10" when stocked. The biologist said he though we had 80% vegetation cover at the time. Thanks a bunch for your advice.