Many professional breeders use UV on their centralized systems. Sure, you can start with clean broodstcok and quarantine, but if anything manages to get in you're sunk. Then you have to medicate the whole system.
The systems from Aquatic EcoSystems, which are designed for use in maintaining valuable and delicate zebrafish mutants, incorporate UV, as does the system Hoff used in the IOH clownfish breeding facility. It provides a margin of safety.
Disease will happen in a hatchery, and it's best to be prepared for it.