A betta is an anabantid which is a type of fresh water fish that has a labyrinth organ that allows it to breathe air in a limited capacity. They are often found in very slow moving to still water that can be very dirty and almost oxygen deprived(hence the organ). The biggest mistake that people make with Bettas is keeping them in those little jars. Yes, they can survive, but it is not ideal. The main problem with the bowls is that they build up nutrients way too fast. Bettas also like to have places to hide. A leaf or lily plant floating on top is perfect. This will also give your fish a chance to "bubble-nest". They will literally breathe in air and create these little bubbles under the leaf or lily to nest in. It is a really neat thing to see. If you are keeping just the betta I would recommend a 10g tank with the smallest little filter you can find. Bettas are great with most other freshwater tropical fish that aren't nippers like barbs. I always kept mine with tetras to add a little flair to the tank. I hope that helps. If you have any questions I might have answers, or can help you find them.