Sick Tuskfish - please help if you can

So I need some help, but 1st I will give you the backstory. Tuskfish acquired popeye several months ago in just one eye, from what I have read that is most likely due to physical injury. I let him be and after a month or so decided to add Epson salts to the tank as wetwebmedia suggests but to no effect. He acted fine and no other fish show any maladies so I did not wish to stress him by relocation to another tank for treatment. About two months ago, give or take, his other eye started showing some problems, so I once again tried the Epson salts to no avail. I already feed a varied diet (krill, silversides, formula 1 flakes and cubes, mysis cubes, pellets, and a couple different marine flake foods) so I didn't try much more, but then I noticed he was having a hard time seeing, so I decided to transfer him to a treatment tank. It was also a good time to totally redo my aquarium adding a sump, algae scrubber, refinishing the stand and jetting some of the poor quality live rock for an vida rock centerpiece but that is for another thread.





Anyway I have tried freshwater dips and then treatments of erythromycin, sulfa, furan-2 following the directions of each but to no effect. I have tried cupramine for copper treatment as well. I have even tried ParaGuard dips. Of course I followed directions and removed medications between treatments with the exception of sulfa as those drugs are well tolerated with others.





His eyes still look terrible and he can't see. I am out of ideas. He has not had any food in a long time, tuskfish carry lots of mass and he does not appear near starvation, but I have no ideas what to do. I hate to see him suffer like this and just now started considering euthanasia but don't know how. I am hoping people can help with treatment ideas.