Ich can appear to be dormant in a tank in that you never see an outbreak till something goes wrong that stresses the fish. But it is possible to have an Ich free tank. Once you do you should QT
everything for 6 weeks before adding it to the main tank.
I removed all my fish to a QT
and left the main tank fallow of fish for the 8 week QT
period. Ich can not survive more than 30 days without a host fish so that left my main tank free, and the hypo treatment insured that my fish were free.
Is my tank free of Ich? I don't know. I have added some corals (without QT
) since the treatment and although I have not seen any evidence of it, it is possible to have introduced it again.