My betta used to be very active and whenever I approached the tank he swam over. If I touched the food container he swam over and immediately ate it once I put it in the tank. Last weekend, I took him to my friend's house because I was leaving for a few days. He was near another male betta but in separate tanks about a foot from each other. On Sunday when I picked him up he didn't eat anything and kept hiding in his house or floating on top of the water. I had the water tested and all levels were normal. I moved him to another tank (4 gallons, heated, filtered) and he seems to be swimming around more and not hiding. However, his swimming is slow and he still spends a lot of the time against the side of the tank at the top. He doesn't look like he has an illness except for his behavior. He still hasn't eaten and it has been almost 5 days. I am not sure what to do. The temp. of the water is 80, the water quality is normal, and he doesn't have any physical signs of illness. I purchased him 4 weeks ago and was completely happy, always building bubble nests until I took him to my friend's apartment and now he won't eat.