After looking again I think its a bacterial infection and either some fin rot or fins that have been tattered from aggression even then bacterial issues and fin rot can happen. Most bacterial issues like this are gram negative. Treat with a gram negative medication would be my thoughts. Something like triple sulfa, maracyn 2 or other similar antibiotics for a full treatment with possible 2nd treatment. Til gone. Nice thing is gram negative meds don't mess with bio filtration. There are other good meds/treatments out there as well.
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