I may catch some flack for this, but once he is treated, if he's still not eating, put him in a separate tank with a bunch of feeders -even ones that you might think are too small for him. He may go for an easy, easy meal. Our recovering pbass just couldn't resist having constant food availible to them and they eventually started chowing down. We had some juvies that got ich and then wouldn't eat -even the rosies were too much for them. So we went to a LFS that was breeding cichlids and bought some of the fry that were teeny tiny. It totally worked. Since yours is bigger you probably won't have to go that far, but rosies (as much as I hate em) might be right up his alley since he's weak.