If you have it on hand then I would use it. If you are going to purchase some medication then I would get Maracyn or Seachem Paraguard. I have never used Maracyn but I hear that some people really like it. I have used Paraguard during quarantine. Hopefully someone with more experience with medication chimes in. In the condition he is in I would get anything that is broad spectrum (parasitic, fungal and bacterial.)