I would not consider this urgent as in the fish wont make it through the night, but I do consider it urgent. I have a yellow tang in my 20gal QT. We received him about a week and a half ago. He went directly into the QT as all new fish do, and he began to get a mild case of ich (less than 10 spots over all, flashing less often than once per hour). I began treatment with copper, specifically cupramine from seachem. He did not get a fresh water dip before entering as I don't have the stuff for a proper dip yet. He is now at the full concentration of copper, has been for 2-3 days (forgot which). The ich seemed to have disappeared mostly around 5 days ago, and he stopped flashing. I haven't noticed any further ich spots since then. Yesterday I noticed he had some black spots on him and he was flashing again (less often than once an hour). The black spots are in total estimating 5-15 of them on the entire body. They are VERY tiny, difficult to see. I would guess that it would be very likely in many people's care they may have gone unnoticed. They are roughly 1/10th the size of a grain of salt and don't appear to be increasing or decreasing in population as far as I can tell. Any idea what this could be? Will the copper treatment also treat this? Is it normal, or just a side effect of copper? Anything further I should do to treat this in addition to the ich? Thanks so much for your help.