I got my betta fish, Finn, about a year ago. As soon as I noticed something was wrong, I changed the water in his tank, and I treat the water before I put him back in. It's been about 2 days and nothing has changed.
He is vertical in his tank, with his mouth at the top like he's gasping for air. He has slight pine-coning and his gills are very swollen and black. He doesn't move except when he floats up to the glass, then he'll swim back to the center of the tank and stay vertical there. He hasn't eaten in about 4 days now. Lastly, his pelvic fin has something weird on it - it doesn't really look like a fin rot, but more like there's some whiteish substance, like fuzz on the bottom of it.
I originally just thought it was dropsy (because of the pine-coning) and accepted that he was going to die, but his stomach isn't really bloated, it's his gill area, so I'm not so sure anymore. Any idea of what it could be and how I can fix it?
Oh and I've had the water level fairly low so that he could reach the top easily.