Pond Boss Forums AQUATIC VEGETATION Controlling unwanted plants Will grass carp eat these weeds

That looks like milfoil, if so then grass carp may or may not control it depending on your stocking rate. Here is list of vegation GC prefer to eat, note that milfoil is low side of the preference list.

http://warnell.forestry.uga.edu/service/library/index.php3?docID=185&docHistory%5B%5D=1