[untamed]

My experience with a cleaner wrasse was that it pestered my existing fish to distraction. It caused an immediate change in general stress level of the tank. It seemed that every fish was darting around trying to escape the cleaner's attention. It was the only fish I've lost that didn't bother me when it disappeared about two weeks later.

Mine never appeared to eat anything I fed.

I'm not aware of the experience that they are capable of removing ich from a fish. That just sounds a bit too good to be true to me. Cleaner shrimp are also sometimes said to remove crypto parasites, but I don't think that is the case either.