Pond Boss Forums STOCKING A NEW POND Types of fish to choose Add Grass Carp or Not?

I have a question that I've been pondering for a while. I've seen many posts that say grass carp are less effective controlling vegetation once they get larger. My question is why? It seems counter-intuitive. Big fish need more food, right? Let's assume a pond that is not pellet fed. Do grass carp change their diet to something besides vegetation when they get larger? How are they keeping those big bodies going and growing if they aren't eating as much vegetation?