What happened to my yellow tang?

Klinson8 · Jan 9, 2019

I had a Cyanobacteria outbreak. Treated the tank with chemiclean and followed the instructions like I have before but the yellow tang was breathing rapid while the tank was being treated. He still ate like a pig as usual. I did the water change and he seemed to be breathing better. I had to dose again and he was breathing heavy again. I was doing the water change after the second treatment and he was breathing heavy and just hanging at the top. He usually still swims and picks at stuff while I’m doing the change. I fed about 2 hours after the water change and he ate. About 45 minutes after he ate I noticed him laying on his side and breathing crazy fast. He was dead within 20 minutes. All my other fish and corals seem fine. My levels are all good and the same they typically are. I saved this dude as the smallest tang I’ve seen at a store who was beat up bad and want to know what happened....any info or ideas is appreciated.