Hi
I wouldn't recommend anything under ten gallon.. The footprint is only 10x20. Gives you room for heating,filtering and many options. They are also cheaper than most smaller tanks. They are also a lot less work than
bowls. I wouldn't even keep a Betta in less than 10 gallons myself. gary

The idea behind a Betta is that it is an Anabantid, meaning that they have a breatjing apparatus that alows them to take atmospehric air. They are indigeonous to areas with poor air / stagnant water. Similar fish include the Gouramis and Paradise Fish.

A 5 or 6 gallon Eclipse will support a Betta nicely and take up little space, but 10 is even better. Bettas may be native to waters with little oxygen, but those waters are not the size of teacups, in in spite of the carp you hear from pet store clerks.

Like all fish, Bettas need room to swim and exercise, so given at least 5 gallons, proper food and clean water, they can and do live far longer than their supposed life span of only a 2 - 3 years.