I have had two different ponds and placed grass carp in each - have had no problems at all other than they keep vegitation down. No muddy water, etc. They do grow rather large after a few years and I have been told the smaller, younger ones are more active in weed control - however, mine have been in four years now and are probably all between 15-25 lbs, and they have continued to keep my weeds under control. I have nothing bad to say about them.
