Question about ick

[rolinjs]

If there are no signs of ick for a certain amount of time, like six weeks, does this mean there is no longer ick in the system? If that is true, is the only way ick can start back up is through adding an unquarantined fish. I am a bit confused.

[The Aquarist]

I don't know if 6 weeks would qualify because sometimes fish seem to get one or two spots and nothing for weeks and then one or two again. Sometimes it doesn't explode into a problem, but I believe that it is possible to have a complete ich free tank. I have run tanks for years and not seen ich. Putting an un-quarantined fish in the tank can easily place ich back in the tank, even if you don't see a big outbreak.