Luvamisol dip is what I hear kills these suckers. A friend used it on these guys with absolute great sucess. Also, green spotted mandarins are know to eat flatworms aswell as black leopard wrasse. Here at the store, we keep black leopard wrasses where ever we have a flat worm problem, in less than a day, the flatworms are all gone. But definately try the luvamisol dip to get rid of the AEFW, and if you want in the end to try and keep them out... the black leopard wrasee... every sps tank should have one
-Mike C.