I used Aiptasia-X on a very tiny one (2-3 mm across). Also, had a larger one pop up underneath a piece of coral that had a gap between its base rock and the rock it was sitting on. Something in the Aiptasia-X makes them want to eat the stuff. You take the syringe, fill it up about 1-2 ml and then SLOWLY move the needle toward the mouth. Hopefully you'll have a steady hand and it won't retract into its hole. If you are slow enough, it will wrap its tentacles around the syringe and then, as close to the mough as possible, squirt the liquid in. My bigger one took 2 tries, because the first time, I was too jerky (standing on a step stool 7 feet up in the air, bent over in half, with one arm down 23 inches into the tank trying to squirt the liquid into its mouth and the base was located in a hole about the width of 3 pennies). If you get enough in its mouth, it won't be able to eat or reproduce. They are not really too harmful to the tank in small numbers but they multiply faster than rabbits and then sting anything and everything that comes their way. If you use shrimp too, it's got to be the peppermint ones, so do a Google search to recognize the difference between those and the camelbacks. Very similar looking, at least to this non-Marine Biologist. HTH. [P.S. To plaigarize one guy's signature line here (my favorite), this isn't Rocket Science...it's Marine Biology.]