Fish with skin, what med works?

[Violet]

I need some advice on what would be the best medication in this situation. I have a with with skin rather than scales, it has a huge white mark on it's body, sort of fuzzy (but just a little) on the edges. It looks like when you skin your knee on a gym floor, not cut, but just like a layer is removed. I have had the fish for ages, there are no ornaments with sharp edges and no other fish are attacking it.
I need advice on (a) what this is (a kind of fungus?) and (b) what medication is okay for a fish like this. Thank you! Let me know if you need more information.

 

[Lotus]

It sounds like you need to use an antibacterial. Scaleless fish are generally most sensitive to ich medications, but antibiotics are fine.

I like the Mardel meds. Maracyn Two would probably work well.

If the mark is huge, a milder medication like Melafix or Pimafix won't work.

 

[Violet]

Thank you so much Lotus, I haven't had to use meds in years so thought it best to double check.