I have to respectfully disagree. All my fish come out of Quarantine healthy fat and happy
If your fish come out fat and happy, they it's not a bare minimum setup. (Thinking tangs in a ten-gallon as "typical".)
Voila! No disagreement! :) :) :)
Once again, it's important not to get distracted by "all the pretty treatments" available.
They have their place (predominantly for treatment of demonstrably sick fish), but what you're after is healthy fish that can resist a disease organism when they do bump into one. That is your goal. And the fish doesn't find that resistance within a chain of treatments. (Though treatments can be compatible with that goal if done with care.)
If one's main concern is for one's current fish then one should have equal concern for one's care routine. Healthy fish will be able to resist a chance disease organism brought in with a new fish. It's not impossible to have fish that healthy.
If your fish are living under stressful conditions, are under-nourished, etc, then they are not going to be very resistant.
If that's how your fish are living, then it's a matter of time before the wrong critter gets by QT, gets by tank transfer, and hits your weak fish. (Count how many threads back in the Disease section you have to count before you get to a failed treatment scenario where a pathogen has made it to the display. Regardless of the theoretical capability of QT and treatments, this is the reality. You need healthy fish.)
It's almost a copout to blame the disease or the new fish.
My list of favorite fish-related care links from R2R and around the web:
And a selection of two from the list:
