11 months seems alot longer than what i have been reading. i thought it was more like two months. there is a stage of the parasite that will lay dormant in your tank for a while. so even if you qt'd new fish, the parasite could still attack the fish if you add them before the parasite completely dies off. thats just what ive read. IMO i think ich can be in your tank and as long as your fish are healthy to begin with and have nothing to stress them out, there immune systems can fight it off. im sure plenty of people will disagree with that tho.