I bought a filefish a few months back, man did he ever clean it up. Not an aptasia in sight, and he didn't even pick at my coral. Then I moved my duncan because it was getting stung by the rose bubble tip, it sucked in briefly, and so after that he thought it was food. I moved him into the 55, he started cleaning it up, then OJ the stone cold killer tomato clown did him in. Not even a trace left of him.
Aptasias coming back in both tanks now, did aptasia x a couple of times, but losing the battle. Bought another filefish last Thursday (this one happens to be a bit smaller) and all he does is swim up and down in one corner of the tank. Doesn't even act like he knows what his job is. We'll see if he learns or not. If he starts picking at any coral I can move him to the 55 (plenty of aptasia in there for him to eat). He'll be fine in there since OJ is no longer living at my house. Figured I can move him back and forth to keep both tanks clean.