I have never used melafix in my life and see no need to. What is the active ingrediant in the cure you are using? A number of drugs will fix white spot---methylene blue, malachite green, acriflavine, quinine, mepicrine, common salt etc. The spots you see are the drug resistant stage of the disease and your treatment kills the vegetative stage that emerges from the spots so you need to keep treating after the spots go away to make sure you get them.