Could be damage from the copper, but I know these fish are sensitive to copper so I was ramping up dosage very slowly. Had only 1/4 of usual dose very next morning my Bluestripe Butterfly was dead and other showing red spots ontheir sides on day three before I added any more copper, telling me it was copper sensitivity. Not sure if they would of reacted that bad to just 1/4 dose in such a short time. Removed copper and dosed furan2 with kanaplex and red spots went away.