Not to be rude, but this is what comes of a bowl / tank much, much, much too small. 1/2 gallon is entirely too small for him, for many different reasons: Impossible to cycle, ammonia builds up so fast, **you cannot heat it efficiently, ***you can not filter it efficiently, ***and you cannot keep a temperature stable either. This is why it's so much better in at LEAST 2.5gallons. That way, you can maintain it with less difficulties.
How often do you water change? In a 1/2 gal, you have to do it practically twice a day. This goes to everybody (and I don't want to offend you, patmcad! Not saying this is your case, but I really want to throw this out here) - fish are not an easy way to get a pet, I've already spent over $100 on just my two bettas alone, and have no regrets spending the money.
Takumi is right, it's best to use regular tap water. It has all the minerals for a betta. Just make SURE you use a dechlorinator because chlorine kills. However, not all tap water is good. Sometimes, people just get plain crappy tap water filled with bad stuff, like ammonia actually in the tap water. That's when you resort to other places. I've never had that happen, so I wouldn't know what to resort to.
And BTW, for the people who sell betta water - those are pretty much knock offs for your money. Again, tap water is best unless the tap water is just really screwed up, lol ;)
I stay away from medications. Always (unless they're DYING, but I've never gotten to that point). I use: super-clean water (as in frequent water changes) JUST for minor tail rot, to prevent stuff. I feed them food soaked in garlic, and aquarium salt. Never had a problem with them. Plus, when you want to heal a betta of disease, it's recommended you heat the water up around 80*F, or a couple degrees higher.
Temp. fluctuations also bring disease pretty readily, since it stresses out the betta. Stress in anybody can affect their immune system - this definitely goes for fish too.
Good luck with your betta, hopefully you take up some of my recommendations! You can find a LOT of cheap stuff on eBay, garage sales, craigslist... and let's face it, Walmart has some pretty decent prices too, even if they do treat their fish like... *ahem*. :)
ANd whenever there is a sale at a pet store, I always GO GO GO and buy stuff I may never use, lol.
Last edited by xxabc; 03-05-2010 at 06:23 PM.