Serpae tetras have gone through some name changes, and it is not always a certainty which particular fish might be in the tank labelled "serpae tetra." Similar fish also appear under names like "red minor tetra" and "callistus tetra." The scientific name of each fish is the only way to ensure the fish is this or that, but of course the supplier or store might get the scientific name wrong. This fish has ben known as Hyphessobrycon serpae, H. callistus, and H. minor. In the most complete work to date on the characidae, "Characoids of the World" (1977) by Jacques Gery, this fish is within the Hyphessobrycon serpae complex which includes four forms difficult to tell apart, H. serpae, H. minor, H. heraldschulzi and the "red minor." It was the view of the late Dr. Gery that this genus and indeed the characidae in general are in need of a review, and this is now in progress.
The serpae tetra has a reputation as a fin nipper, although some writers maintain this is only within their own species. In my view, the caution should be taken seriously, and I would avoid putting this fish into a community tank unless you have separate tank space to place the fish on its own should trouble in the community tank occur. It is not just the possibility that the fish might nip at others, but if the fish is somewhat bullying towards other fish, even if no actual physical damage results, the other fish might be severely stressed and thereby succumb to disease and eventual death. I once acquired a group of rather small fish for one of my large tanks, and everything was fine for a couple of days; on the third morning I noticed that most of the other inhabitants in the tank were hidden among the plants, and during the day I realized that they never came out into the open. Then I saw why; the small fish I had added simply chased them, never nipping or doing any physical damage, but the other fish became so hounded that they literally hid shivering and shaking in the plants. I removed the offenders and things returned to normal within a day, although an outbreak of ick ensued, undoubtedly brought on by the stress to the fish.
I would stay away from serpaes; there are several similarly-shaped and coloured tetras that are perfectly safe, fish like Rosy Tetra, Bleeding Heart Tetra, Red Phantom (and Black Phanton) Tetra, Flame Tetra, Roberts Tetra, etc.
MBilyeu has good advice on stores and thinking ahead before buying any fish. The ideal thing is to have a good reputable aquarium store and make it your "headquarters" and get to know the staff. In such stores the staff are frequently hobbyists themselves, and their advice can be invaluable. Pet departments in major stores are usually not so knowledgeable; I remember going into one such store near me, and the two employees in the fish section knew that the little critters swimming in the water were "fish" but that was the extent of their knowledge. Not a good place to buy fish from in my view.
You mention there are no fish stores near you, so perhaps you could find a good one that you can get to once in a while, and keep in touch with them. The manager or staff probably have email, and in most cases wouldn't mind corresponding with you if you want to know what fish they are getting, or if you would like them to try and get some, as MBilyeu said. Always know what you are buying before you buy it. You don't want to buy a nice looking fish only to get it home and discover it killed all the others overnight.
While writing this, I see MBilyeu has responded, and another good suggestion; tell us where you are and we may have suggestions.