Update: During the copper treatment of my DT to eradicate ick and velvet, I decided it was a good time to make a few changes to my livestock to minimize aggression from some of the large tangs. I removed and gave to a friend my large Sohal, Purple and Blond naso tangs. I also moved my medium-large Powder blue tang to my home system. As this was also a good time to add new less aggressive smaller fish, I added back a smaller Powder Blue tang, medium-large Achilles tang, and 4 Lyretail anthias (1 male, 3 females). To avoid aggression from adding the 2 new tangs, the remaining Orange shoulder and Yellow tangs were temporarily moved to the sump. I have already removed most of the copper from the system and all fish appear to be disease free and doing well. It will be some time before I can remove all traces of copper and replace corals.
