My Gem Tang is not looking good something is going on. I did an H2O2 bath when I got him and did not see anything. The LFS told me he treats all fish with copper & Prazi. It gets stressed when I turn the light off in QT (Observation). After 15 days I moved him to DT thinking that would help with the stress and I don't have any other fish. He eats everything, breaths normally, no scratching. After 50 days he looks bad. Feeding him three times spirulina flakes and frozen food. Pls help.