Black Knife; Unknown disease

Hi all
My Black Knife Ghost has come down in what appears to be white cotton like patches on his side. Its definitely not white spot. Hes acting normally but I know this is not normal. Should I put him in a hospital tank straight away with Triple SUlfur tablets or other medication? Cheers

 

Triple sulfa would work, you could also do a combination of Pima and Melafix. It sounds like a fungus to me, but what is often overlooked is that fungus' doesn't show up typically without a bacterial infection which in turn doesn't show up with out a wound of some sort.
I would do this, put in hospital tank if you can, and add an established filter, last thing you need now is to put him in a sterile tank and get ammonia burns or worse... Treat with an antibacterial, antifungal, medication like the couple stated or metronidazole or sulfathiazole.
If keeping in the tank, do a nice, 30% or so W/C THEN start the medicine. Most fish do not get sick unless they are getting bullied or the water quality is off.

Good luck and if treating in the DT remember to take out your carbon and do a water change once the course is over!