Need Help with J. Dempsey

Hi All,

I have a Jack Dempsey cichlid that is slowly dying. He's 13 years old
so I think he's just dying of old age. He hasn't eaten for several
weeks and he's lying behind his cave nearly motionless. His fins move
just slightly and his mouth is open and just barely moving. He is
emaciated to say the least.
My question is this - Is there a humane way to put this fish out of
it's misery. I've read of some methods but I don't think I could
actually go through with them. I hate to see anything die slowly like
this so I'm hoping somebody has an idea out there.

Thanks for your suggestions, Tom D.