I agree on placing the Bfly back in the QT
but I would not use copper. The evidence thus far doesn't support it's use. Once acclimated to the QT
, lower the salinity some over the next few days down towards 20 ppt
or so. This will have a "soothing" affect on the fish and reduce significant stress after all the shipping and moving around. As the fish regains osmotic balance, it can often times rekindle the feeding response.
Be very careful how you catch the Bfly as it will already be severely stressed. You don't want to compound that with being sick and push it over the edge. FWIW
, in future allow all new arrivals to remain QT
'd for no less than 4 weeks. This allows a proper adjustment period for the fish and you enough time and opportunity to react to potential threats to the main display and the fishs' health.
As far as what your fish does have, a pic may or may not be of any help but it sure could be a start. So far I'm leaning towards trematodes... any additional symptoms no matter how small would be of great help. In the meantime, I would look around today
at a few LFS
to see if any have prazipro or meds containing Praziquantel.