I agree with BurnNspy. Remove the sick fish if possible. I tried MelaFix in my reef tank before. It is a tea extracts and does no harm to coral. It did not work for me because I still lost my royal gamma to ICK. Just a reminder, Skimmer should be off when adding MelaFix. Skimmer will create trememdous air bubbles inside your tank if it is not off. Reef corals like mushroom, polyps will shrink and close up when MelaFix is added. I tried for a week and there is no affect on my corals. Anyone use this medication before and have experience with it?