I bought a betta fish about 2 years ago. It was never very active. Lately he is not active and today I saw him U shaped. Lately I have seen him sleeping sideways and I gave him break from food. He only eats Aqueon betta pallets. I used to give him 2 pallets morning and evening. Now I have cut it to 2 pallets since he does not come to eat twice a day. I checked the water levels, Ammonia 0 PPM, Nitrite 0 PPM, Nitrate 0 PPM. I cycle water every week. Temperature at 78.6 C. I use water heater and I change filter every month. Any advise?