Ich, oh, how I hate that stuff! Quarantine those fish, baby! Also, don't buy fish sold from copper treated display tanks. It hurts their immune system if they have been in it long enough, they are probably being treated for ich because they have it, and because many stores don't check copper levels they under medicate and breed copper resistant ich. And quarantine. No skimping, at a bare minimum 4 weeks with zero symptoms before adding fish to the display. Buy a magnifying glass to check your fish out pre-sale and while in quarantine. I don't care if people look at me funny, I've avoided some bad stuff by looking very, very close.
I've had ich, black ich, marine velvet, dropsy, bacteria and fungus - mostly in quarantine. Injured fish - fin nipping, scale nipping, and injured anemones - caught in powerhead due to sponge failure, injured corals - buried by fish or pinched between rocks.
