jack dempsey, please help asap!

Question
Ron,
Thank you for getting back to me so quickly.  Tonight when I got home, "Jack" was belly up on the bottom of the tank.  When I approached him he struggled to turn himself right side up (and actually did it for a few seconds) before falling back over.  He now has a milky colored turd that won't disconnect from his body.  He's struggling so much to stay alive and I don't know what to do for him.  
I wrote one if the other "experts" from this web site the other day.  I just received his response and he suggested salt for muscle spasms and meds for gill disease.  Do you think that could be what's going on or should I throw in the towel? I'd feel better about medicating him if you both had similar ideas.  
It's just so hard to explain what's going on to someone who's not here.... Anyway, any further ideas would be wonderful.  
If it turns out that he is just old, what is the most humane way to put him out of his misery....?
Thanks so much for all your help!
Lindsey
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Followup To

Question -
Thursday morning I noticed that my Jack Dempsey was curled up like a banana on the bottom of the tank.  His breathing was heavy and seemingly very stressed.  I did a partial water change, filter change, and then treated the water with "fungus eliminator".  It's friday night and there isn't any improvement.  I've kept fish most of my life and they've always been very healthy.  I'm at a loss here on what to do... The african cichlid and green terror that share the tank with him are ok so far.  "Jack" is about 8" long and I've had him for about 6 years.  Is it just the end of his life span or is he sick?  If I remember correctly, my oscar was behaving similar just before he died 5 years ago.  Do you have any ideas on what is going on?  I live in rural Montana so access to this kind of thing is limited (except for what I can dig up on the net).  If you have any ideas on what I could try, I would appreciate it.  I know it's just a fish but he looks like he's suffering...
I look forward to hearing from you!
Thanks
Lindsey

Answer -
Hi Lindsey,
 He isn't just a fish, he is YOUR fish, so I understand completely (I have similarly had particularly fish for many, many years, so I know what you mean). I think, however, that he is just old.  The symptom you describe is often what I see when a fish gets old and sadly there isn't anything you can do about it.  Sorry.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


Answer
Hi Lindsey,
 The most humane way to put him out of his misery is to freeze him in a bag in the freezer.  I would only do that if there is absolutely no hope that he will recover.  

 Personally I don't think much about the salt idea or the gill remedy. The fish's problems are internal. Sorry.

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>