The closest fish store was out of tetracycline, so I didn't get the tetracycline in the tank until today. I turned on the heater, and the water temp is now ~72F. I've been doing water changes weekly, but I will increase to daily. It might be my imagination, but maybe he has been a little more active since the addition of the tetracycline. Not sure, but maybe.
I've been sprinkling food in the tank every now and again, but I'm not sure if he's eating it. He doesn't come to the top to eat when I put the food in. Occasionally, he will swim a couple laps around the tank, but with no control, bumping into things, etc. He might be able to grab a piece of food when he does this, but it doesn't look like food is the goal when he swims like that. I'm hoping he is able to pick up a piece or two off the bottom of the tank.