and i love the harlequin shrimp also...and so does all of the customers that see him in the tank.
cmor- no. nothing was added, and the population steadily rose for 1.5 years until one day i saw them on the zoas and a few polyps were closed up. then more and more...i started knocking them off to see the bite/suck marks.
i also had massive amounts of them in my home system and they never touched a thing. btw, i believe they were originally introduced via rock and corals from my home system.
i started the tank with 150 pounds of kaelini rock that was drop shipped, but it's just more logical that it came from my starfish colony.