Stock the grass carp in late spring or early summer. First step is to get a stocking permit from the TPWD. It takes about a month but is no big deal. They will give you a list of sources. I paid $15.00 each for them and they come to you at 10 to 12 inches long. Pretty bass proof. They totally eliminated pondweed for me. I stocked 7 in a one acre pond. Only 2 are still alive after 4 years. Both are over 3 ft. long and have mostly lost their appetite. I need to get some more to take care of some milfoil, or hope they will eat the milfoil.