I'm trying to find out the pros and cons of stocking our backyard lake with grass carp to control hydrilla. Our lake owner's association wants to do this. I know they live about 10 years, grow up to 10 lb, can completely remove all aquatic plants if there are too many carp which creates muddy water & no place for little fish to hide & increases algae bloom if there are not enough aquatic plants, Supposedly carp are people shy and would not bother swimmers. They are omnivorous. Does anybody have any other information that I might be able to share at the time of the association's vote on this issue? I NEED HELP. 
The one's swimming around Miami are sterile so population control is not a problem, they get WAY bigger than 10lbs... (saw one in Davie like 50-60lbs... maybe it wasn't a grass carp, not sure) they eat fruit, corn, and bread and are a sucker for trebble hooks... so If you notice the lake habitat in decline just take a few out.
Just an average fisherman.
You want to get the Triploid Grass Carp. I have about 6 of these in my lake in my parents neighborhood.
They are huge probably 4-5ft and around 30-50lbs but they are people friendly the kids in the neighborhood
feed them: bread,lettuce, and spinach. They keep all three of our lakes clean. The HOA put them in and posted signs
saying they are protected and to not fish for them but if caught please release unharmed.
Here is a list of all approved suppliers of the Triploid Grass Carps in FL.
Hope this helps some.
http://www.ecy.wa.gov/programs/wq/plants/management/Vendor.pdf
Grass carp are a great way to reduce weeds. Note: they will not control algae like most people think they will. My pond is stocked with grass carp and there is still moderate weed growth, but not nearly the out-of-control levels that it was at before. And the rest of the the fish population has remained steady 5 years after stocking. Grass carp don't really root around and muddy up a pond; that is mainly caused by Common Carp when they're looking for crawfish or other invertabrates hiding in the bottom. Grass carp are also a blast to catch. They often come to the surface to eat grass clippings after we mow, and can sometimes be convinced to take a fly made from green yarn that looks like grass. Blast on a fly rod!
i thinks carp get bigger. ive seen some at least 30lbs and they may attack. i had 2 bass on a stringer on the side of the boat and a carp grabbed the bass and rip them into pieces and all that was left was one bass head.
I had some in my pond when I moved here about 15 years ago. After they died off I was inquiring about them and was told I need a special permit to obtain them. So I dropped it but if anyone has to many and needs to get rid of a few I sure can use a few. They sure keep down weeds on the edges of the pond. I've never found any problem with keeping othe fish in there with them either. Looks like you have plenty of positive info to report. I wonder about the permit to obtain them..... This fl. the permit state. Money can buy almost anything. You can go as fast as you want, catch what you want etc. just pay for a permit, or fine and all is well.