Showtime305 wrote: You can probably leave them in QT for 2 weeks. The only sure way to rid you tank of ich is to QT all fish for 6-8 weeks. While they are in QT treat with hypo-salinity or copper. The main thing is to leave the display tank fish free for a long period of time. The ich will have no host to live on and all the parasites will die. If you don't want to do a full QT then put them back in after a couple of weeks hopefully everything will be fine. Don't forget to vacuum out the bottom of the QT to remove any parasites that fall off of the fish. What treatment are you using?