Hi guys can you help me identify what this is and recommend treatment? Currently it’s in a 75 gallon qt tank running some copper under .8ppm and I dosed knaplex and metroplex as well as prazi in the past 2 weeks, running carbon at the moment.
Is the fish breathing and eating normally? What copper product are you using? I don't recommend people staying at low doses of copper - it leaves your fish open to protozoan infections.
This looks like it could be bacterial, but the pic isn't super-clear. I base that on me seeing a lighter center spot on what looks like a roundish lesion - and bacteria often grow in colonies like that. How did you dose the Kanaplex? Did you do all three doses?