I agree with LargeAngels - Cupramine. Hypo brought immediate relief for my adult and juvi Imperator angels. Here is what I just wrote on another thread regarding hypo and my emergency use of Cupramine.
"I had an ich outbreak last month and treated fed the fish with garlic and Vitachem four times a day. All but 3 fish showed signs of improvement which were breathing heavily and scratching themselves (An Adult Imperator, Blue Tang and an Juvi Imperator). They went in a 50g qurantine tank and I brought the salinity down to 1.009 over 24 hoiurs. The next day all three fishes showed remarkable improvement and the ich spots went away. On the 2nd week of hyposalinity things went downhill again. The three fishes were breathing heavily and all three showed light faded patches all over the body. No ich was observed and FW dips confirmed no flukes. The blue tang did not make it and I was puzzled so I could only think that the fish came down with Velvet because of the light patches. Since I could not use Cupramine (Copper) in hypo I had to rush the salinity from 1.008 to 1.0013 over a few hours and according to Seachem that I could use Cupramine at 0.20 (1/3 stregth) in hypo situations. Adult Imperator at this time was laying on its side breathing heavily. It was semi-stuck on the powerhead so I had to move the powerhead. The Juvi imperator was swimming in circles and upside a few times while laying on its side and the Blue Tang did not make it. The two remaining fish were like this for 2 days and I pratically wrote them off but continued the 25% water change daily and increasing the copper level and salinity. Miracously I looked into the q-tank yesterday and the adult imperator swam up to me wanting some food. I threw a few pellets in and it ate but not as much as when it was healthy. Today the juvi imperator stopped swimming in circles and upside down and ate very few pellets. Im hoping conditions will continue to improve.
Even though hypo brought immediate relief for my ich infested fish I had to watch out for a possible Velvet outbreak"