Well sadly he did not make it thru the night. I gave him the 90 minute bath then placed him in the qt tank medicated with the antibiotics. After the bath I did notice that more of his side had peeled away.
I would, however, like to learn from this to help make sure I can be quicker to act in the future so let me recap what happened.
On Saturday I picked up the purple tang. I asked the LFS what SG they keep the tanks. He stated 1.019 and I matched my qt to that. I did notice that when I got home the water had a yellow tint to it. I assumed it was low level copper. Also since the color of the bag distracted me, I forgot to double check the SG.
I let him settle in and tried to feed him some nori without luck.
On Sunday I dosed a full dose of CP as I did not want to wait for symptoms to show. I fed him some LRS herbivore mix and he ate a good amount.
Monday I went to work, came home, fed him some LRS again. He ate it and was swimming great. I observed him for about 10 minutes. All was good I turned off the lights and went to bed.
Tuesday I got home late because I got stuck at work. I turned on the lights and saw the terrible infection that I posted earlier.
So what could have caused this and could have it been avoidable?