QT help needed. Lionfish and tang questions

[Pretty_fabulous]

We recently purchased 4 fish. Yellow Tang, Sailfin, Blue Jaw, dwarf Lionfish.
They were all put into a 40gallon tank with egg crate dividers.
The yellow tang is deteriorating fast. Fins are falling apart, eyes cloudy, laying down, not eating.
blue Jaw was swimming sideways. Only using right side. Still eating.
sailfin is fine. Eating A LOT! Happy and swimming.
lionfish also seems well, eating its live food swimming or just hanging around.
We dipped the 2 tangs and the blue jaw. The yellow and the blue jaw had flukes. The yellow was VERY BAD! The blue jaw had a few. Sailfin, nothing. We didn’t dip the lionfish as we couldn’t find any info regarding it.
the fish are all now in NFG and general cure. Is this bad for the lionfish? We 100% believe in QT, but would it be advisable to move her to the DT, or should she go in a separate QT? We think at this point copper is needed, but we knew better than to treat with the lionfish in the QT.

Any help is appreciated.
thanks

 

[Big G]

Welcome to R2R

Best to not treat the lion with copper. While some may survive, many will not eat. And those that do survive copper don't usually live very long.
Better to treat with CP

 

[Caseyoidae]

Welcome to R2r!
Probably should put in separate qt. I’d try to avoid this fish seller in the future though. Hopefully @Humblefish can chime in. Very knowledgeable on the subject.

 

[Pretty_fabulous]

Welcome to R2r!
Probably should put in separate qt. I’d try to avoid this fish seller in the future though. Hopefully @Humblefish can chime in. Very knowledgeable on the subject.

Thank you. Humble fish actually jumped on my Facebook post last night and was incredibly helpful.