I got clown fish on January 4 ( about a month). I used copper power in the QT tank for 4 days and stopped because the clown fish weren’t eating, and noticed that the clown fish were pooping, white stringy, poop. I did 100% water change and use Kana Plex instead for 3 measure (about 6 days, maximum dose), the clown fish started eating as soon as I added the kana plex and the white stringy poop disappeared. After a week and a half, I added the clown fish into the display tank and then took it out because the nitrites were above 5ppm (tank was still cycling, no livestock in display tank). Three days later I add copper power in the QT. Three days after that , I noticed the clown fish had white stuff on its tail, fins and gills and had fin rot. The clown fish are still eating. I did a 100% water change every three to four days in the quarantine tank because of ammonia. I don’t know what type of disease or bacterial disease is on the clown fish. It is my first time handling with saltwater fish. I was wondering if you guys could help me identify it?