I’m hoping you’ll can help me diagnose what my blue tang has. These are new fish I added a month ago. I know I should have QT them first. But either way I had pulled all my first 2 weeks ago from my DT after my sailfin was showing signs of ich/velvet. I immediate got them into QT and dosed copper power to the recommended 2.5ppm and kept it there. The sailfin died the next morning(attached photos in case that helps). Fast forward a few days and all fish looked ok except they were still breather a bit heavy. Then after 10 days the blue tang started scratching again. I did a fresh water dip yesterday to check for flukes. I now see part of his tail fin is turned red and some white stuff on its head. What does it have and why isn’t copper working?