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New Ich Fallow Period


Dr. Fish
Content Moderator
Feb 3, 2017
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First off, I must thank @victoly for bringing this recent study to my attention: Effects of temperature and host species on the life cycle of Cryptocaryon irritans

It has now been peer-reviewed and the findings verified by other scientists. I'd also like to share a couple of other related studies (below):

These studies verify what we have all long suspected: Lower temperature slows down Ich's lifecycle, whereas higher temperature speeds it up! Of course, we must still keep in mind that different strains of Ich might react differently to various temperatures. However, based on the information below I feel confident that raising aquarium temperature to 27C/80.6F can shorten the Ich fallow period to 6 weeks. Also, two studies now suggest that raising temp to 30C/86F can shorten the fallow period to just 2 weeks! I am confident that nitrifying bacteria can survive 30C, but not so confident about corals & inverts. :( So, raising tank temp to 30C might be a strategy best used in a FOWLR system.


CAVEAT: You must still eliminate any hypoxic/anaerobic regions in your tank whilst going fallow. If a protomont crawls into a hypoxic environment before encysting, it may go dormant and all bets are off! This is probably the "real reason" behind most fallow failures. More information on Why a fallow period will sometimes fail can be found here: Fallow periods: Going Fishless