Pyramid butterfly disease ID

[machmachmach]

I just lost a pyramid butterfly in my quarantine tank. It’s quarantining with a purple tang, powder blue tang, gem tang, and a mandarin. It has what looks like an open wound on one side near its tail fin. Any idea what this might be and do I need to treat the other fish? None of them are showing any symptoms. The pyramid was eating normally until this morning when it looked lethargic.

 

[Jay Hemdal]

Did it arrive with that fin damage? If not, there may have been some tankmate aggression.
What have you been treating the QT with?

An open wound like that could be the protozoan, Uronema, but this lesion looks too open to be that, it may have been a bacterial disease.

 

[machmachmach]

It didn’t have that fin damage when I got it. It’s been in quarantine for 2.5 weeks with 1.75ppm copper and a 5 minute freshwater dip before introduction to the QT. All fish were from the same LFS and introduced together.

 

[vetteguy53081]

I just lost a pyramid butterfly in my quarantine tank. It’s quarantining with a purple tang, powder blue tang, gem tang, and a mandarin. It has what looks like an open wound on one side near its tail fin. Any idea what this might be and do I need to treat the other fish? None of them are showing any symptoms. The pyramid was eating normally until this morning when it looked lethargic.

This fish is de-scaled and with torn fins and either uronema or scavengers opened it up after death looked to be a result of aggression. At any time have you noticed any given fish antagonizing it?
A fish with yellow coloration will often be a suspect

 

[machmachmach]

I never saw any fish antagonizing it. There is a powder blue tang in there though which does have some yellow.

 

[Jay Hemdal]

It didn’t have that fin damage when I got it. It’s been in quarantine for 2.5 weeks with 1.75ppm copper and a 5 minute freshwater dip before introduction to the QT. All fish were from the same LFS and introduced together.

Just an FYI - coppersafe or copper power needs to be above 2 ppm (2.25 is the target) for it to work properly, below that, and it won't stop protozoan disease issues. I don't think that's the issue here - just for future reference.