I used distilled water at room temp, about 73*F-75*F. It is in 1 gal of water with some standard aquarium rocks and a plastic plant with plenty of hiding room. I don't know the ph or anything else really.
I was feeding it both the Betta pellets and frozen brine shrimp. But it seemed to like the shrimp better.
I have only had them for about two weeks and in that time I've cleaned the tanks twice.
The only real odd thing I noticed with this one fish was yesterday there was a slick layer of what looked like oil on the surface. I cleaned him immediately though.
Okay, first thing is first.. Aaaaaah! No distilled water!
Fix that immediately. Use some kind of water other than distilled (tap/spring) something, because distilled is awful for your bettas.
Some nutrients in water, the bettas do NEED. Distilled is empty of everything and anything beneficial to your fish.
You need to grab yourself some dechlorinator and tap water quick.
This could be the reason your betta is so listless.
Secondly, you should really get test strips to test your water in case of ammonia spikes, etc.
And in a 1 gallon aquarium, you should be WCing them every.. 2 -3 days, because of the small amount of water.
Also, you might consider switching plants to a silk plant that won't tug on his pretty, silky fins.. And perhaps making him a cheap cave using an old yogurt cup, or something else that would need to be washed with scalding water and peel the stickers off.
Also, you might consider getting a heater, because that temperature is a bit low for bettas. They are tropical fish, after all.
Perhaps a heating pad or something similiar?
They should be around 75 - 82.. Ish.