Melafix is derived from Tea Tree oil, but I wouldnt use it regularly, like you would a water conditioner. As previously stated, any living thing will develop a resistnace to meds that are over-used. FWIW, I use one dose of melafix when there is a rough netting (not often) or if I see evidence of fin rot starting (not often), in addition to extra water changes. It works for me.
