I know alot about this. I had it and read everything I could. They feed on the fish and as long as there are fish in your tank, ikk will be there. If you move the fish of your tank and AT them, the ikk will die after a month or so, because it has no host. Copper sulfate is the only thing you can treat them with and it actualy hurts the fish. In all my many experances with ikk. I would say throw the fish out that have ikk, if not all your fish and just start over agian. That may sound bad but if i had to do it agian thats what i would do, or you can qt them and treat them, but you cant treat them in a tank with coral and waht not or everything dies. The chems are nasty. So trust me, if you dont have alot of money in fish dump them. If you have big investsments in them treat them. I spent a month reading everything I could find on it. Some fish like flame angles don't take kindly to treatment. Latter. email me if you have more questions. Its a pain.