sick emperor angel, I have no idea what it is!

I would also say skin flukes treatment Prazi pro 5ml per 20g for 5-7 days do the whole 7 day teatment. You have to remove carbon and adjust skimmer os it does not skim but you want it to inject air into the water so make it as dry as bosible. It's the only thing I have found that is a liquide and seems reef safe. The only thing it afected in my tank was a long pink tip Nem but he recovered with no noticable afects. It will also get rid of any flat worms you have also and tape worms and a few others. Ithink the dose is so small it only kills off the very small bugs.

Bill