I've had my betta for about eight months. He used to be in a 2.5 gallon tank with a heater, filter, and lamp. I'm pretty good at staying on top of weekly water changes and do a full tank clean every 3-4 weeks. About two weeks ago I noticed he started sitting between the glass and his heater and not moving. After monitoring him and checking the water for about a week, he got worse and started laying on the bottom of the tank or hiding in his car. I bought a 3.5 gallon tank complete with a new filter, heater, lamp, and decorations and bought water treatment supplies and a different food. He's been in his new tank for a couple days now and still seems super lethargic. I can't see any visible signs of illness, his fins are still colorful and not torn, his eyes and gills don't appear swollen, and there are no stress stripes or spots. He hasn't eaten the past couple days and doesn't even acknowledge his reflection when I tried getting him to move around with his mirror. I love my lil guy and am just not sure what to do from here. Help??