Dave, I have a lubbocks fairy wrasse that absolutely loves flatworms. I had some benign flatworms appear in my cube a while back, and any time I lifted a frag plug off of the sandbed, he would immediately swim up to my hand and pick the flatworms right off the bottom of the plug.
I had been debating selling him before moving my current fish over to the new cube...only because my stock list is at it's limit and I have been wanting to pick up a mystery wrasse. Let me know if you're interested at all...~3 inches and healthy. Never had any fish diseases in my tank, and I just put all of those fish through a round of prazi-pro as a preventive measure before moving them to the new cube. Catching him should be a breeze since he eats out of my hand.