HMmm... I never heard of clowns being prone to ich. Tangs, yes. I would never put copper in my tank. You can treat ich other ways. Try to set up a quarantine tank under your display tank. It will come in handy if you ever have an ich outbreak. Also, if you feed your fish garlic soaked food, you are helping them to increase their immune system, therefore they are better able to fight ich off. In essense, all fish have ich...but when they are stressed, it just takes over, and they can't fight it off. If you do have an outbreak, you can use hyposalinity in the quarantine tank.