Hi all, looking for your guidance. I have a red tailed shark who is close to 11 years old. He has not eaten for last 2-3 days. He had a fungus like growth close to the mouth. I was doing Pimafix and Melafix treatment for last couple of days. That fungus growth seems to be gone but he is breathing extremely hard and keeps coming up to hit the water surface which he never used to do. Today, I did a 40% water change and started the Kanaplex treatment. Water readings also seem to be fine. Nitrate is at a higher side and close to 40 but that has always been the case with this tank. Its a 35 gal tank. Pls guide.