This is often overlooked by many people and relates to us humans right now so much. The best prevention to disease is good health. If you support your tank inhabitants with a good diet and water conditions as well as a balanced stock, you will have a system that can handle stress. I personally have never QTd in 10+ Years, never had fish disease. Maybe I got lucky but it probably has to do with the health of the system.Personally I hate dealing with fish disease because no matter what I do I feel like it always sneaks it’s way in so I try to focus on fish health so that way their immune system can always fight off whatever is thrown at them. Firm believer in feeding well with a good nutrient export system