I'd agree that it's HLLE. Also, make sure the fish is getting an adequate amount of greens in it's diet. Nori should be offered a few times a week. Soak it (and all foods) in supplements like selcon or zoecon (available at most good lfs). Angels are grazers and constantly picking diatoms and algal film of rocks and glass. Thet get a good deal of their nourishment from algae so make sure you're offering it. The flake food and mysys are "okay" but it really needs a much broader diet. Try things like Emerald Entree, Marine Cuisine, New Life Spectrum pellets, even some minced clam every so often. I think with a better diet you should see a gradual improvement. I purchased an Eibli angel before with a small touch of what your seeing and it recovered nicely within a month or so.