The fish, Sergio, is not doing so well. First, I must admit that at 4 1/2 years, Sergio is very, very old for a betta. And he's actually quite active, attacking his food and waving his fins at us if we are a bit late on feeding him.
Lately, though, he's taken to either lying on his artificial grass or hanging vertically in the water. Neither of those positions seem all that healthy. Also, instead of attacking his food, which is awfully cute--it's a pellet, but he hunts and kills it, he now sort of lunges towards it and if he misses, well, he sort of takes a nap and waits for the next meal. We really try to drop the pellets very close to his head, but he's not very interested.
Worst, though, is that Dave noticed that his gills are getting crusty. We do not assume this is a good sign.
I wish there was somthing we could do to ease his pain, short of using gin or the freezer. However, I think we'll just continue to provide him with whatever comfort we can (usually a head near his bowl and some sympathetic sounds) and then just flush him when he's officially belly up.