Okay this might seem silly to some of you but please bear with me. My old beta fish Ping whose at least 4 years old seems to be dying very slowly. Over the last week or so he's been unable to swim properly and mostly is laying on the rocks on the bottom of his big bowl. When I feed him he tries to come to the surface but is mostly struggling and swimming as if his swim bladder isn't working properly (sort of sideways and almost flipping over on his back poor thing).

Now I know it's "only" a fish but this is my pet and I do really hate to see any animal die inch by inch. Is there anything I can add to his water that would humanely end his life? He's barely able to get to his food so he's likely starving to death and I just don't want that to happen. I can't just remove him from the water and let him die that way...seems too awful to me to do that.

Any idea my fishy friends?