It would really help if you can get a clear still picture of him so that we can see the body more clearly.
Fins are frayed and patches of white are present, and left eye is severely clouded. This can be a number of things is you want the honest truth.
For now I would continute the full regimen of Melafix and also start a dose of Pimafix as the two work great together and address different symptoms harmoniously.
If Ich is an additional factor, a separate med will be needed, however a cocktail of those two until you can provide a clear still image should help with the fungal infection present, and attack secondary bacterial infections. Don't assume it was harmed by chemical collection - these diseases are the most common and easily contracted and are seen in about 75% of all fish sold through mass suppliers (Petco, Petsmart, WalMart, etc., etc., etc.) Mainly this is because most of them have no idea what they are doing, don't have the time/resources/space/give a dam to QT new arrivals, or have looped systems where disease spreads like snot on a playground. Swimming still seems within normal range and weight looks healthy, so you are not in the "OMG!" Red Zone quite yet.
Once you provide a pic, I can make a more definite assessment as to whether you are dealing with Ich as well, so please do so soon.
-Emi
--Moving to Disease forum--