Heater for tiny betta bowl

[leek86]

Me and my little sister went to a local betta breeder monday to get a betta for my tank, while we were there my sister saw bettas can be kept in relatively small containers, the breeder told her a few litres is fine for them. So my sister ended up getting one too, on the way home she got him a fish bowl which is about 4litre.
Weve found out during the day the ambiant temp of the room leaves the bettas bowl at around 24 centigrade which is about right, but at night the temp drops and winter is coming.
Can anyone reccomend a heater for a bowl this size as the smallest I can find say for 20litre tanks and obviously we dont wanna over heat the little guy.

 

[clearancepuppy]

You also do not want to have a cheap glass heater explode and burn down your house. The betta would be better off in a 10 gal with an solid metal heater. You need 10 watts to each gallon of water.

 

[Laser]

I would try to get him into a 3 gallon tank. 5 or 10 would be better, but a 5 shouldn't take up much more space than the bowl. They do make heaters for betta bowls, however.