my friend has a small betta bowl (one half gallon?) and it used to house a male betta during last summer, but when winter came it got too cold in the house for the betta to live in the unheated bowl. how do you heat a betta bowl? shoud he just buy a bigger tank that can hold a heater or is there some other type of heater, like a heating pad that can be use (in the winter the house is 62 degres F.