Habitat/Care: Bettas are one of the most recognized, most colorful, and often most controversial fish in the freshwater hobby. Debates range on about the appropriateness of keeping them in small bowls. To fully understand their needs it is important to become familiar with their native habitat. Bettas originate in the shallow waters in Thailand (formerly called Siam, hence their name), Indonesia, Malaysia, Vietnam, and parts of China. They proliferate rice paddies, shallow ponds, and even slow moving streams.
Although many fish keepers are aware that Bettas come from shallow waters, a key factor that is often overlooked is the water temperature. These countries are tropical, which means the water temperature is quite warm - often reaching into the 80's. Bettas thrive on heat, and will become increasingly listless when the water temperature falls below 75 degrees F. Water temperature is perhaps the biggest argument against keeping a betta in a tiny bowl (which cannot readily be heat controlled).
Even though Bettas do well in waters low in dissolved oxygen, that does not mean they require less oxygen than other fish. Bettas have a special respiratory organ that allows them to breath air directly from the surface. In fact they inherently must do so. In experiments where the labyrinth organ was removed, the fish died from suffocation even though the water was saturated with oxygen. For this reason, Bettas must have access to the water surface to breath air directly from the atmosphere.
Optimally the water for keeping healthy Bettas should be soft, warm, with a neutral to slightly acidic pH. Water movement should be kept to a minimum, which means that power filters and powerheads are not suitable. Bettas may be kept in a community tank as long as the water conditions are met, and if no aggressive or fin-nipping fish are present. However, only one male may be kept in each aquarium, unless they are separated by a barrier.
The use of plastic boxes that hang inside the aquarium are a suitable option for keeping more than one betta in a tank, or for keeping them in a tank with fish that might nip their fins. Females will generally not fight with each other, and may be kept in the same tank.
NOTE: Selling a betta in a vase with a Peace Lily has become in vogue. However, a flower vase is not a suitable environment for the betta.
Taken from
http://freshaquarium.about.com/cs/anabantids2/p/betta.htm
