One of the most common misconceptions of betta fish is that they must be in a bowl all by themselves. Mostly because of the stories that they are fighting fish and because these fish are seen in stores in those little plastic cups.
While Bettas don't get along with their own kind, they can make a good community aquarium fish and get along with other community type fish. I've have one with tetras and an angel fish without any problems. Because they are used to being in confinement and are very shy by nature, I found that it likes to hide in the caves and plants I had set up in my aquarium. Having plants, artificial or real, is important for housing a Betta in a community aquarium.
It's been very popular lately to have a betta in a bowl with a plant in it. While the plant may look good and make a nice display on a desk or end table, bettas are carnivores....in other words, they don't feed off of the plant. They need to be fed food formulated specifically for them like any other tropical fish.
As with any fish, it is better to house it in an aquarium with a filter. However, if you do decide to house it in one of those bowls, it must be cleaned out frequently, as it needs fresh, clean, de-chlorinated water. Otherwise, the water will contain ammonia caused by fish waste and uneaten food. The ammonia is toxic to fish.
Bettas have a special respiratory organ that allows them to breath air directly from the surface. In fact they inherently must do so. Bettas must have access to the water surface to breath air directly from the atmosphere.
In their natural habitat, Bettas often come from warm, tropical climates. Bettas thrive on heat, and will become increasingly listless when the water temperature falls below 75 degrees F.