Concerned for my new betta?

As long as your temperature is 68 degrees to 85 degrees, your fish should be ok! However, he would be much happier and healthier if his temperature were around 80. This helps make them more active, helps them heal and prevents them from getting sick as often. I would get a heater, as they are not too expensive, and it couldn't hurt. Thanks for getting a real sized tank, unless most people who cram their beautiful bettas in tiny jars!