Well said. I suppose in certain circumstances there might be a few medications that work. I've tried most of them, and I'm 100% convinced that I've done more harm than good trying to treat fish diseases.In my experience, treating sick fish is often difficult, expensive, and/or doesn't work.
For those that have healthy fish and haven't had problems, I salute you! You obviously have a good source of healthy fish and take good care of your fish. But you've also had a little luck.
Don't suppose though that a UV sterilizer is a sure-fire device that will forever rid you of the worry of diseased fish. Waterborne critters are the only ones that a typical UV unit can zap. Waterborne transmission isn't the only pathway for one fish to infect another.