Here is what I would do if I had a BTA that bleached(which I've had before due to...experimenting with lighting/spectrum) assuming water quality is on point, and life support system/lights are in order + some totally anecdotal comments.
1. Target Feed small mysis shrimp
-twice a week - needs time to consume, digest, and poop. Remember: one hole for all functions
-no large foods. Without their zoo partners helping true food consumption is their primary way to gain energy. Large food requires more energy to
attempt to consume (that mouth has to open wider), and theres no guarantee a larger food item wont just get spit out.
2. Do a lighting acclimation cycle over a week (or two)
-If you don't know how to do one, hit the lighting section here and guarantee you'll find a guide.
3. Seek consistency - avoid tinkering w/ any doser settings, or trying any new snake oils or regimens, or tank temps. Good time to double check your heater and/or chiller + take a peak at that skimmer too (just a good idea IMO if you have a critter not doing well. I'm not suggesting anything is kaput in your gear, nor that any gear needs cleaning/maint but no one wants to have a heater fail when they're trying to heal a critter!).
-I may get blasted for suggesting it, but I would even consider delaying water changes for a week (or month...or two...), UNLESS you've got something that requires it (e.g. WC is your nitrate export method, or tank has sps/lps corals and WC is your alk/ca replacement method). You know your tank better than me - exercise your best judgement with that
+1 to taking a while to regain its color
Just some totally anecdotal advise bud(just to reiterate). I'm no nem expert, but just a guy that's had BTAs for years. Hope it works out for you and your nem. GL and happy reefin'.