Ich will look almost like grains of salt sprinkled onto the body of the fish. There is a known lifecycle and the ich (if there is any) will be visible and then it will disappear (many think the fish kicked it) but it is really just going to the sand to reproduce and will come back so make sure if you see it you take the proper measures to rid the fish of the disease before you put it in your display tank. I believe I read somewhere that the shape of the body has a lot to do with tangs being so prone to ich. It was saying something about any fish who has a body that is as tall as it is long (tang, butterfly, angel) are more prone to disease, although this could have been talking about something else and I just have a bad memory. Can anyone else recall?