First of all,
You are indescribably wrong. Never ever take the first few research sites you read as gospel, and for the love of god don't ask a breeder. The way they keep their fish is absolutely disgusting and cruel. It's also been touted as normal throughout most of the US.
First off, I'll show you what a bettas wild habitat looks like . I'm showing you this because it will demonstrate that bettas do not and never have lived 24/7 in a small puddle of water.
http://www.google.co.uk/imgres?imgur...1t:429,r:2,s:0
http://www.google.co.uk/imgres?imgur...iw=800&bih=403
Does that look like a few gallons to you?
No. It's thousands of gallons of knee deep heavily vegetated water.
It's a popular myth, particularly in the US, that bettas are fine in very small quantities of water because in the DRY SEASON
( note the words dry, and season neither of which denote the presence of large bodies of water for long periods of time ) bettas can survive in small muddy puddles.
( I have joined my fair share of US populated betta forums to see if this is a widespread opinion and horrifically it is )
Now that is pefectly true, they can survive. If the puddle is big enough not to dry up completely ,or they are lucky enough to be able to flip to a nearby puddle when theirs becomes intolerable. But thousands don't get that lucky. Thousands upon thousands die in their mudpuddles because the levels of oxygen grew too low and their labyrinth organ simply couldn't deal with it.
Survival is just that. A fight for life in hard times. There is no logical reason to recreate this in a glass box unless you are some sort of sadist.
You are not entirely to blame, as you have been fed incorrect information and popular myth.
2.5 gallons is NOWHERE NEAR enough water for that species to live in permanently. It is really, seriously NOT that much better than a Walmart cup.
The reason for this, is he hasn't got anywhere near enough space to swim. 2.5 gallons is a tiny amount of water, and these fish DO like to swim regardless of however much people who keep them incorectly will have you believe.
5 gallons is the absolute bare minimum, 10 is better, more than that is better still.
Not only is swimming space the issue with 2.5 gallons, water quality is THE most important thing about keeping any species of fish. You don't keep fish. You keep water, and the fish are a nice benefit.
The fact you think doing a couple of water changes a week on a pot of death shows you clearly know nothing about the nitrogen cycle, and why you NEED a filter. Not just to make pretty bubbles but to keep your fish alive.
Read and comprehend: http://www.liveaquaria.com/general/g...al_pagesid=102
Where on earth did you get the info that because they can breathe atmospheric air, bettas for some reason don't need filtration to keep the water free of toxins, and effectively stop them from living in their own shit and piss?
Do you honestly believe that breathing air would make bettas magically able to resist disease from water pollution?
Seriously I would actually like to know where this info is coming from because whoever is spreading that needs shutting down asap.
Filters clean your water. The fish shits and pisses in the same water it's living and breathing in. Two water changes a week on a tank as tiny and insufficient as yours is nowhere near enough.
Also, air is added to the aquarium through surface agitation.
Even on a five gallon filtered tank you will need to do one 50% water change per week.
Basically your entire setup is completely wrong and will end up killing your fish far short of it's lifespan. Did the places you've been getting your info say that the avergae lifespan is 1-2 years? Because that's also wrong. When kept correctly bettas can easily live for five years. All of mine have so far.
You will require the following:
A FIVE gallon tank or larger ( second hand is vastly cheaper, and yes, you do have room for five gallons, everyone does )
[b]A sponge
filterB] ( and airpump to run it ) these are safest for bettas as they have a low flow output and won't suck the fins in and trap them as a power filter would . If you can't get one of those, then a small internal cannister filter will be fine, as long as you ziptie some fine plastic mesh over the intake grills, and use a spray bar attachment for the outflow nozzle.
You already have the heater, this should be set at 27 degrees C.
Plants. NOT plastic. Plastic plants very often have sharp edges that will catch on and tear the bettas long fins. leaving the fish wide open to infection.
Use silk plants or live ones. Live are best.
These fish come from waters which are heavily vegetated. The common phrase often touted is that these fish don't like large spaces. It's WRONG. What they actually don't like is OPEN spaces.
The disliking large spaces thing is basically desigend to encourage people to buy up small gimmick tanks which cannot keep anything alive.
You ( as in people in general ) buy a small tank, your fish endures it's 1-2 years of misery, it dies. You think that's perfectly normal ,and that you've done everything fine and go and buy another, and the cycle repeats itself. You're feeding a money making machine and torturing something that can't even run away.
If you really want to keep this fish healthy and give it a decent existance, then PLEASE read what I've written and put it into practice.
I am more than happy to help you help that fish and keep it correctly. Keeping fish is a surprisingly addictive past-time, and when it's done right it's really rewarding to see them all living healthy lives in a well kept tank.
I'd be more than happy to answer any questions you have about setting up a tank correctly and keeping a betta. I've kept fish for near on 20 years now.