Yes, they were quarantined. Fish are a purple pseudo chromis and an indigo hamlet. Both were healthy but have been sparring constantly. My best guess is that the infection set in where scales/fins etc were damaged by sparring (since infection tracks apparent damage) and other fish are unaffected. I'm going to attempt to remove at least one of the fish and give it away (likely the hamlet) but I'd prefer not to maintain a long term treatment tank if possible.