I'm trying 1/2 a fish/acre in one of my lakes. Grass carp eat 2 1/2x their body weight per day. That's a lot of plants. Unfortunately our experience with grass carp is it's an all or none solution. But I think mostly we get impatient and don't give them a chance to get big and eat more. Everyone wants veg control in just a couple years. I'm trying the patient approach.