Dead discus

[swifto]

Hi,last night I feed my discus as normal at 5pm,I noticed that my 15cm red melon didn't eat.
About 1hr later he was in the corner trying to hide by 9pm it was dead.There was no illnesses or other signs to suggest it was gunna die.
All 5 other discus ok not affected or stressed & eating still.Water is ph-5.5-6.0,ammonia-0ppm,nitrite-0ppm,nitrate-0ppm.
So with ever thing seeming normal is it possible it just sustain organ failure,I've had this discus for three years,no new additions to tank for about three months.
Any thoughts.

[Woodsie]

Sorry for your loss mate. I had something similar years ago but I suspect he had an aneurysm because I actually saw him all of a sudden madly dash all around the tank for about 90 seconds then side ways flouder then was dead. Everybody else was fine. He was the healthiest thing.

[swifto]

Its just that in the 3yrs this & one other have never been sick.

[phil56]

It's almost impossible to know the real cause of death without dissection.I have had similar deaths where I found a 5cm long bright red worm had perforated the intestinal wall and latched onto the organs of the fish.Types of foods can have a similar effect on fish from intestinal blockages.Fish that pig out are more prone.Axelrod put forward many years ago that many young Discus died from DDT poisoning found in foods such as Brine shrimp when fed to excess.Blood worms can also poison fish through heavy metals.
The fish that overeats the most dies first as he accumulates the most poisons.
The trouble is unless you open him up we will never know for sure,could be 100 reasons. Good luck with the rest.