So I just looked up "how many grass carp to stock/acre" and found anywhere from 5-10, ok so in my 60 acre lake that would be 300-600 well listen I'm telling you they put in 225-250 and there has not been a single strand of vegetation for 8 years. So what is it? I'll tell you what it is it's a pure guess sometimes it works sometimes it doesn't, sorry but I'm a dentist and that's not how I treat my patients or in this case "manage" a lake. Grass carp are a way for hatcheries to make money.