My bangaii cardinal is dying. I've had him for about 2 years. Several weeks ago I started noticing that it seemed to have its mouth open quite a bit. But it was still eating somewhat. Well over the last week I haven't observed it eating at all. So two evenings ago I moved it to my quarantine tank. Its not eating. Its lying on its side at the bottom of the tank and seems to be gasping for air. I actually thought it would probably be dead by the end of the day. I don't seen any signs of it having been picked on, or any other physical signs of an illness. I have a bottle of melafix and have tried some of that each of the last couple of nights. Any suggestions???