I didnt QT one fish i bought... Bought a goby on tuesday.. On wednesday i went to a special breeder to buy 2 clown fish... Clowns were definatly healthy as he has a very specialized setup...
My goby ended up having ICH, infecting my clowns, and then the goby jumped out of the tank and dried up..
Now I have ICH and i have to setup a QT for 6 months b/c of my "risk"
dont gamble on that one fish with a issue could do alot of damage i know first hand...its not a fun thing...if you have a qt might as well use it