[Spottedleaf.]

Betta's do live in puddles, but that is only in their most dire and driest seasons. That usual results in them trying to jump from that puddle to something bigger and that and conditions in the puddle can end up killing them. In the wild betta's have long territories that can span from a small area to a large area, sometimes it is deep but usually it isn't too shallow. In aquariums betta's thrive in large aquariums with their own territories and fish to keep company. Usually (with my experience with a 20 gallon and many others experiences) they do great together and will even swap territories every once in a while. Small tanks that are less than a five gallon can stunt a betta's growth or kill them to larger parameter swings because of the small body of water. Pet store's use the small containers that they are in to save space because betta's can't be kept in small spaces together and they can take in air from the surface of the water. This has caused a bad rep on betta's only needing small tanks. At least it can cause stress to the fish. Your betta will thrive and love you and enjoy his/her lifes to the fullest in a big tank with appropriate tank mates that will help simulate your betta and not have it getting bored to death.

(P.S. The boy above posing is based off of my betta Pantalimon aka Pan)