I also agree with a 30 day observation period. You must remember, a fish is very stressed when it first arrives in a new aquarium, no matter what conditions are present. Other fish can sense this, and will relentlessly harass the new addition. Quarantining helps the fish prepare for life in a display, with established animals.
A perfect QT set-up is a 20-30 gallon (I prefer a 55 gallon) with various clay pots, artificial coral or PVC hideaways. A sponge filter powered by an air pump works best, as carbon and other medias remove medication, if any has been used. I run a sponge filter in my sump at all times, in addition to the sponge filter in my QT tank, so that I can quickly set-up a separate hospital tank, if I need to treat a new arrival.
A perfect QT set-up is a 20-30 gallon (I prefer a 55 gallon) with various clay pots, artificial coral or PVC hideaways. A sponge filter powered by an air pump works best, as carbon and other medias remove medication, if any has been used. I run a sponge filter in my sump at all times, in addition to the sponge filter in my QT tank, so that I can quickly set-up a separate hospital tank, if I need to treat a new arrival.

