So my betta is almost a year and a half old. About 6 months ago, he got fin rot, so he's pretty much just a body now (it's pretty sad :-( ) but he seemed healthy until recently. He won't eat (or even look at food) and he sits at the bottom of the tank all day. He doesn't react to my finger or anyone coming into the room like he used to. I've tried changing his food from pellets to brine shrimp flakes, but he won't even get off the bottom of the tank! His tank is clean and he has a good heater and filter. What's wrong with him?? I really don't want him to die.