Help with id, brown spot on green chromis

[Greenjeans]

I have a small school of chromis going through quarantine, and one has a brown spot on its side. It hasn't seemed to change in the last week, eating and behavior seems fine, and no other fish have a spot. Is this from injury, or do I need to treat for something?

 

[Big G]

Couple of thoughts. Sometimes chromis pick each other off one by one. So it could be a wound. Watch for aggression. The other is the dreaded uronema. I'd strongly consider treating for uronema. It's deadly and quick. Once you see the sore area turn red, it's usually too late to save the fish. And if one has it, the entire group has been exposed.

Uronema marinum

Uronema marinum What You Need To Know: * These are the red sores most often seen on chromis damsels; however it can afflict any fish. * Treatment of choice is a 45 minute formalin bath (e.g. Quick Cure), followed by transfer into a new/sterile QT. * Once in QT, it is very important to do...

www.reef2reef.com

 

[Greenjeans]

I have absolutely been seeing some aggression - it's too many chromis in too small of a QT, my mistake as I'm learning. I'll keep an eye on it and may treat with metroplex proactively, thank you.