I took some corals from my brothers tank last week, he called me this morning and said all his fish have ich. now that i look, i'm seeing what might be ich on my 2 dominoes and my puffer, all fish have been in tank for a while and are not stressed or ill and show no signs of ich except the spots, all very active and eat well. actually puffer looks like he might have a spot on his left eye.why would they get it and what's best treatment w/o using Cu? Think it'll just go away? i have no quarantine tank.