ich runs in a 48 hour cycle. it attaches to the fish for about 24 hours then falls to the bottom of the tank and procreates. there has to be a fish in the tank for the ich to reattach to, otherwise it dies. so, if you take one fish out and put it in a different tank they ich cycle will start in there and the fish in the original tank will eventually catch it. the best things are the things ive read. salt, ich treatment and turn up the temp. the salt helps the stress the treatment kills the ich and the increase in temp makes the ich run through the cycle faster. any ich treatment should be used a second time 48 hours after the first. good luck