My Cory has a cotton/white fungus on his left lower fin

Have done the following:
- 5 days of Maroxy.
- An addition 5 days of Maroxy and Maracyn with no change.
- Partial water change and filtering with carbon.
- Added 1 table spoon aquarium salt to 10 gal. tank
- On second day of Seachem Sulfathiazole. No change.

Request advice and alternatives.

Thanks in advance.

Clark Stillman