All fish are still doing well in the hospital tank, except the yellow tang. Friday at lunch he was eating, swimming around normally. Everything seemed to be going ok. Friday night I noticed he seemed very disoriented and was swimming on his side. I checked him a few hours later and he was laying on his side. I started worrying that there was ammonia in the tank, so I did a 50% PWC
and moved the yellow tang to the DT temporarily. He seemed to improve almost immediately, rather than laying on his side he was up swimming - still disoriented but swimming rather than laying on his side.
Got up Saturday morning and he had died. No clue what happened, as all the other fish in the hospital tank are still ok and doing fine.
I have stopped the copper treatment for now. Will start it again if I see anymore signs of ich. I've read that tangs are very sensitive to copper, and that could be the cause of the yellow tang's death. But the kole tang is still doing fine, no spots for about 3 or 4 days.