The only black spot disease that I am aware of, cannot be treated by meds.
See my following comment for more info on how to resolve black spot disease:
https://www.monsterfishkeepers.com/forums/threads/black-spot-disease.662463/#post-7454556
See my following comment for more info on how to resolve black spot disease:
https://www.monsterfishkeepers.com/forums/threads/black-spot-disease.662463/#post-7454556