My betta was nearly a year old when this started to happen one day. He was fine in the morning, I went out came home around lunch and looked at him as I came into the room and saw that his head was tilted back and he wasn't able to swim, just struggled at the bottom. The neck around the gills was very lightly coloured instead of the usual dark blue. There was also a rather large lump on the left side just under the gill. I'd like to know what was going on with him that day, I left him alone hoping that he'd get better but by the second day I knew he wasn't going to get any better, instead he just rested at the bottom unable to get to the top to get his food so I did the best thing for him and put him out of his misery. Later after I knew he had passed and had chipped of the ice around his body(I had placed him the the freezer in a plastic baggy with water to put him out of his misery.. the only way I know to put it out kindly) and noticed that the lump was very hard. Any ideas what could have happened to Splash?

I have a betta too that has a lump on his side but he has had it for as long as I can remember having him. He hasn't seemed to be in any pain or had any problems though. Sorry that I'm not much help.

freezing them might not be the best way to put them out of misery.