Hi Sadie,
Don't worry about asking any question here - I'm always happy when someone cares about their betta! <img src="/images/graemlins/smile.gif" alt="" />
I agree with Karyn that if you can swing it, changing to a 2 gallon tank would be terrific - the space they take up isn't that much different than a 1/2 tank. But if you do stick with the 1/2 gal, Rico must stay solitary. Bettas are more lone wolves than social butterflies anyway! You can put objects in front of the tank to entertain him - even a picture of a betta or a mirror for him to admire himself, but not constantly. You are your bettas favorite toy and friend anyway. <img src="/images/graemlins/smile.gif" alt="" />
Be sure to change the water frequently, but I'm guessing that your bettas problem may actually have been not acclimating him to his new water chemistry. Any time you change water chemistry, even though bettas do well in a variety of conditions (you'll find all sorts of water recipes on the internet), they do need to be acclimated to the change. To do that, float them in the new water. Faith from
www.bettatalk.com recommends as much as 24 hrs, and I've had the most success with her method. Float the little guy in a cup or large plastic glass with some of his regular water. Give him about an hour for the temp to equal out, then add very tiny amounts of the new water every 30 mins or so.
Also, I wouldn't recommend putting a heater in a 1/2 gal tank. You can use a light over the tank and that warms the water - you can find adjustable desk lamps with a regular light bulb - as well as finding warm spots in your room when the room temp is lower than 75 degrees.
Cheryl