The fish is not doing so well...

Just as I thought the betta would surely make it. I'm not sure now. He's keeping low and has ignored his food twice. He pays no attention to his mirror. He's either is sick or depressed, fish forums say. Some googling suggested he might be too cold. We don't have any warm lamps that we could put him under, and I'm not sure about the advice I read on-line to add warm water. When I saw him swimming, for just a few seconds, I found myself running to the tank around the kitchen counter, saying "Hey, baby! That's it, little one." By the time I got to the other side of the counter, he was still.