Hi, I'm Kevin. My Betta Black Currant Icecream isn't doing well. He's in a 5 gallon tank by himself, There's a hang on the back with the flow turned all the way down. The water parameters are all normal. The temperature is 30 degrees celcius (Normal in Chennai, India). I got him 2 months ago but for the past couple of weeks he's been very inactive, He stays at the top or at the bottom of the tank for most of the day. He eats well and I give him Hikari Betta Bio gold (twice a day, 3-5 pellets a time). He seems lethargic now and he doesn't raise his top fin as he used to do when I got him. I did have some Java moss in there but I removed them now (they started rotting). I do a 20% water change weekly. I can't see any white spots on him, nor can I see any tears in his fins. He doesn't have a swollen belly either. He looks sick, but I can't find out what the problem is. The guy at the local aquarium where I got him said it's because of the sudden dip in temperature and the fish would be fine if I keep him at 30 and put some salt in. What should I do? Can you help me?