I've had them last only a few days - couple months. It all depends upon how strong the fish's natural immune system is at overcoming the harmful bacteria or virus.Has anyone had viral noodles/ bacterial tuffs only last a few days instead of longer than 7? My regal tang is still getting one of these on and off for about 4 days at a time and then it disappears. It's no where near as bad as when she was in copper for 10 day's though. I'd say she's getting a little sick from the sand bed constantly being disturbed by my new diamond Goby after the sand was left uncleaned for 2 months during QT.