[ImAlyce]

Hi there! I have two bettas and they live in a bowl and a tall vase without any kind of heater. I used to have another betta that lived for three years in a vase without a heater. My question is, do I absolutely need a heater? And if so, do I have to buy a tank for them that has one? What should I be looking for?

 

[DragonFish]

Bettas can live, and if you stumble upon a hardy one for a good couple of years, in a small unheated container....but this is no quality life, and I'm sure though that one you had hung on for a while you had a few others that didn't last quite nearly as long.
A dog can survive in a cold, dirty, small cage for quite some time, but that doesn't mean its a good environment. Its the same thing. Bettas can survive in a small, cold container but they don't ever thrive.

Contrary to the popular myth passed around, betts are in fact a true tropical species of fish, meaning that in order to live a full, happy, thriving life they require a regular. stable temperature of 78-81 degrees Fahrenheit 24/7 year round.
In most places, even if only to keep the water temp STABLE as fluctuations can be stressful, this does require an aquarium heater.

What you want to look for with a heater is something fully submersible, and adjustable with a thermostat. STAY AWAY from present heaters and pad-like heaters that you can't adjust, they can easy under/over-heat and are very unreliable.
Hydor makes some fantastic heaters, just about everyone I know of that has one loves it. Elite is also a great brand, you can find them for a good price on Amazon(they say they're present heaters, but they're actually adjustable). Personally I'm a fan of the(adjustable!)Aqueon brand heaters and Petcos own brand that they sell, both have worked well for me.

Bettas are also naturally very active fish, and they do require much more space to stretch their fins then a little bowl or vase. Along with a heater, yes, you will want to upgrade your tanks(something large is much easier to stably heat anyway). Anything 2.5+ gallons will work, 5+ gallons being ideal of course.
Aqueon is actually having a wonderful sale on their 2.5-5 gallon aquariums.
http://www.petco.com/product/10313/...-Kit.aspx?CoreCat=shoppingHomeOffer_fishTanks
You'd have to remove/baffle/replace the filter probably, but its a great deal.

 

[babystarz]

Well, if you want to crank your house's heat up to a constant 76+ degrees it'll be fine, but otherwise it's just not a good idea longterm. A betta will be too cold below 76 degrees and that means its energy will go towards burning up its own resources to survive instead of to growing the best fins or showing the brightest colors or boosting its immune system. In the end, you see a shorter lifespan and less natural defense against illness.

I agree that an adjustable heater is necessary. Even a cheap one from China off eBay will do, and those are under $10 including shipping.

 

[RoMay]

The Marina Betta Mini Heater is the one my betta uses when she was small enough for a half gallon, and now she's in a gallon. The thing is though with smaller bodies of water the lid needs to be off or the temp will go up to far. To prevent jumpers you can use plastic mesh. I am not an experienced betta keeper but this one has kept my tank steady and warm. My room lacks any heat and it can get pretty cold despite it being in CA.

http://www.petsmart.com/product/index.jsp?productId=12315584&f=PAD/psNotAvailInUS/No

http://www.amazon.com/Marina-Light-...sh/dp/B000HHO9CG/ref=pd_sim_sbs_petsupplies_1 <-- Another good one if your room isn't to cold.

 

[ImAlyce]

I went ahead and got me an Aqueon Heater and a tank divider that I'm going to
put in my ten gallon that way they will each have five gallons of new room and cozy heat Thank you for all your help!

 

[DragonFish]

Oh I bet they'll both really enjoy all that space, that sounds fantastic!