My brother's betta hasn't eaten since we brought him home, about 6 days ago. He's been staying at the top of the tank, in a corner since then. But this morning, we found him at the bottom of the tank, upside down! His gills look inflamed, and he seems to have trouble breathing. He is in a filtered 2 1/2 gallon tank, with a heater, keeping it around 79 degrees. Is he going to die? Or is he just really sick? I've read something about Swim Bladder disorder... Could he have that?