The ideal size of a Betta tank should be around one gallon of clean water per Betta fish. Betta can be frolicsome and fun if they are given enough space. Betta fish can and will occasionally jump out of the water, so it would be a good idea to place some type of lid (with plenty of air holes) over the tank. Now the lid should not impede the Betta fish from getting food from the surface or stop it from getting fresh air outside the water. Betta fish have the ability to breathe oxygen from both water and the outside atmosphere so they need to have clear access to the surface without the worry of falling out of the tank.

A popular fad right now is a "Betta in a Vase" which involves placing a Betta fish in a medium-sized to large vase with some colorful marbles and a peace lily. This type of setup does not qualify as a Betta tank. Although it is very beautiful to look at it amounts to torture for the fish and should be avoided as such.