Quote from that article in regards to cleaner wrasse: (Part 2)
"While probably not able to affect a cure in a full-blown infestation, the use of cleaner shrimp may help with a mild problem. I wish to express my dismay when seeing cleaner wrasses, Labroides species, offered for sale. The vast majority of these are doomed to waste away as they are obligate feeders of marine ectoparasites (Fenner, 2003). There are many other effective cleaners available with a much better survival rate. Please leave these fish in the ocean where they can live long, happy lives and help maintain the health of the other reef fish.
The other argument against the use of Labroides wrasses is, being a fish, they are just as susceptible to infection as the fish they are "treating." In a closed, contaminated system, the cleaner wrasse will, in time, become infected too. As a result, it will eat less and become useless for combating Cryptocaryon. This same argument also rules out the use of other cleaner fish such as the various Gobiosoma species. While these make excellent aquarium residents, they are not an effective cure for parasitic diseases of fish. The cleaner shrimp, on the other hand, are not susceptible to Cryptocaryon and could therefore help to bring about a cure, while not being a complete cure in and of themselves.
One last note on Labroides wrasses, contrary to popular opinion, they do not consume Cryptocaryon parasites. They have demonstrated a strong preference for gnathid isopods, which make up between 77 and 85% of their natural diet (Grutter, 1997 & 2000). The remaining prey items are composed of scales, parasitic copepods, and non-parasitic copepods. So, regardless of whatever conscientious objections one may or may not have regarding their availability in the marine aquarium trade, they are not going to help in the battle against Ich. Also, since Cryptocaryon irritans is known to be rare in the wild (Bunkley-Williams & Williams, 1994), it would follow that it is unlikely that Ich makes up any significant portion of any cleaner organism's diet. This, coupled with how deep the trophonts embed, throws into question the effectiveness of any cleaner against Cryptocaryon irritans."