You cannot determine if they are 'fine' just by looking at them. While their bloated appearance seems to be normal,
any and all fish should be quarantined for 2 weeks before being added to your main tank. This allows enough time for any unseen problem to manifest itself. If they do fine after 2 weeks (some people prefer 4 weeks), then they should be fine to move to your main tank.
Keep in mind that whenever you buy a new fish, that fish has recently gone through a major ordeal just to be shipped to your LFS. Then you get the fish which includes more netting, more transportation, and more water composition changes. All of this really stresses out even the healthiest of fish.
This level of stress lowers the fish's immune system, making it much more susceptible to any disease or parasite that happens along. So when you put your new, highly stressed fish, into your main tank, you're playing Russian Roulette. It's only a matter of time before you add a fish with a disease that infects all of your fish in your main tank.
When you use a QT tank for 2 weeks, you are first giving the fish a chance to recuperate from all the stresses of being shipped to the LFS and then moved to your house. There are no other fish in the tank to fight over for food or territory. You can (and should) do extra water changes to ensure excellent water quality. The fish are able to be better acclimated to your water conditions without other stresses affecting them. And if the fish does get sick, not only will you see visible signs within the 2 weeks, but the fish are in a tank that's easy to medicate without harming any of your main fish, inverts or plants.
Are your fish okay? Probably. But that's really not the question to ask yourself. The question to ask yourself if what are you willing to risk. If you won't mind throwing away all of the the fish, inverts and plants in your main tank, tearing it down, sterilizing it, re-cycle it, and then start all over again, then by all means, put the fish directly into your main tank. But if you would mind that potential disaster, then put all fish in a QT tank for at least 2 weeks before adding them into your main tank.
Also, minimize your risk by never buying from "box stores" (PetCo, PetSmart, WalMart) that do not make their entire living off of fish and ONLY fish. Get to know the owner of the store and find out what precautions s/he uses to ensure healthy fish. And never buy a fish on the day it first arrives at the LFS. It's best to wait at least a week. Most better LFSs will QT their new fish before even letting them be sold because they care about their fish and wish to maintain a very high reputation for healthy livestock. Otherwise, do the general tips of checking out the tanks in the store, avoiding any store with lots of dead/sick fish (this is especially true when all the tanks share a main filtration system so that diseases travel from any tank to ALL tanks).
And you thought you were asking a simple "yes/no" question!
