I have some asterina starfish in my 180 gal. It's not a major problem, yet, but I know sometime soon I will need to irradicate the little boggers. But before I go out and get a Harlequin, I already have 3 cleaner shrimp and a fire shirmp and fairly large bristle sea star in the tank....Do I need to remove them first before I get a Harlequin shirmp?