What type of fish is it and how large/small is it? Personally I have never used a quarantine tank with any of my fish. If you know the dealer is reputable, you have observed the fish know when it arrived at the store you really don't need a quarantine tank. Bowls don't work for qt tanks. The tanks themselves should be filtered as well. They? More than one fish?
If you haven't qt'ed fish prior to this, why are you worried about qt'ing them now?
I would totally nix the bowl idea here. Chances are without a filter don't expect them to live very long. Not to mention the stress you are putting them under in a bowl. This in itself could lead to ich.
