get a large seringe (sp?) and fill it with a number of things... any of these will work, boiling water, lemon juice, or there is a product that i believe is reef safe, but you might want to check it out... its called jack's juice, or joes juice.... i htink its one of those, and the other one is a bait spray for bass fishing...lol....Inject any of those things at the center of the stalkie thingie... thatll kill them and the pepermint shrimp will eat anything else.
a copperband will get too big for your tank anyways. so thats not a good idea.