Blue (Regal) Tang won't eat after being ill

[Frank D. Yerrace]

I have a blue/regal tang that seemed to eat fine for a week or two after
purchase. Then it became ill with (I believe) marine velvet. I moved it to a
20 gallon treatment tank and to my surprise she seems to have recovered (a
couple freshwater dips, some copper treatment).

However, as far as I can tell she hasn't eaten anything since becoming ill.
It has been about 6 weeks! I'm fairly new to marine aquaria (after having
done freshwater for 6 years) and I'm not sure what food would be most
enticing for her. I've been trying Formula Two and occasionally Formula One,
sometimes with Garlic Xtreme as an attractant. I've yet to witness her eat
since becoming ill.

Does anyone have some advice on how I might revive her appetite?

Notes: I still have her in the treatment tank. The main tank is 110 gallons
fish-only populated by 1 yellow tang, 1 picasso trigger, 2 tomato clowns,
and 5 blue damsels.

Thanks for any advice.

Frank