MrTuskfish
Team RC
Cleaner shrimp and cleaner wrasses have no effect on ich. First the ich is below the skin, secondly stomach assays show none ingested.
If you care to read a study where they examined the gut contents of cleaner wrasse or Labroides dimidiatus you can find it in the Marine Ecology Progress Series, volume 197: pages 241-246 that was published in May of 2000, Alexandra S. Grutter. They found that the largest portion of their diet consists of gnathiids which is a parasite, but it is not ich. Parasitic copepods, non-parasitic copepods and scales comprised the remaining portion of the diet. They did not find Cryptocaryon irritans in the stomach contents of any of the fish they examined. Similar studies on cleaner shrimp have been done.
Good stuff! Why doesn't it surprise me?