Petco is having a sale right now w/a membership card for $1 per gallon. So you can get a 3 gallon for $3. But I think that's in-store only. I don't recommend a heater for this tank, considering it is plastic and I would be worried it would melt or cause fire.

And another think..Who is "them"? You know you can't keep 2 bettas together, especially in that size tank, right?

 

You can easily get a tank at petco right now super cheap and membership is free..

Small downside is that I think the $1 per gallon is on 10 gallons and up, but I might be mistaken, worth checking out though. You can always call the store to verify before driving over.

 

Heaters do okay in plastic - I have had two of mine in kritter keepers with 30w adjustable mini heaters and they're fine.

But putting a heater in that -shape- is really difficult... For twelve dollars, you could get a Kritter Keeper or the like with the same gallonage or more, with flat sides that will support a heater's suction cups way more easily.

http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias=pets&field-keywords=kritter+keeper

The XL is 5.90 gallons, apparently, and the L is 3 gallons.

Though I notice a few people say on the reviews there that the tank arrived in the post cracked.. so maybe worthwhile buying from a pet store rather than by post.

The only heaters I've seen that will sit a bowl shape well were not terribly good or reliable, little heat pad things.

 

I have 2 Betta's in 2 separate bowls. And I checked the Petco sale and it's for 10 gallons and up and I don't really have the space for that, and I don't really have the money right now to upgrade to the critter keepers. The back side of the bowl is flat though so maybe I can stick the heater on that? And if not will something like this be fine?
http://www.amazon.com/Hydor-HEATER-...JLPFE/ref=cm_cr_pr_product_top?ie=UTF8&coliid=IFHA3ANMMS66K&colid=1E33Q5I4W11NW

 

The bowl should be fine. I use heaters with plastic storage containers.

Also the $1/gallon sale STARTS with 10 gallon tanks. Anything smaller is regular price.

I would suggest the Hagen Elite 25 watt heater. Its adjustible and not very tall so it would fit more easily into a smaller tank but one of the petco pet keepers is cheaper and would be easier to get the heater in there since its not a circle shape

 

That is a 2-1/2 gal it looks small, but for that size and that price, yea I would rather go with a Kritter Keeper and you could save on shipping, unless that is what you already have, but it is a good size so a small heater might work, could stick on the back of the bowl..acrylic is better however for heaters, and Kritter keepers are acrylic..plastic could melt..I would double check on that with the company to make sure, you don't want to risk fire.

 

It is actually a really big bowl, I looked at the critter keepers at petco and the bowl actually looks bigger than those to me. I'm going to test out a heater in the bowl and monitor it very closely first and if it doesn't work out then I'll get different tanks, probably the x-large critter keepers. Thanks everybody for the help!