Fish curling into C shape, at death

[jesusjones]

Does anyone have an explanation for why a fish that is sick/dying would curl into a C shape once it finally does die? I have had this happen in two tanks, with different species but it just happened twice to some newly acquired fish.

Pygmy cories (wild). They were seemingly OK, small and a little skinny and not stuffing their bellies like the others, but they scavenge around at least. Then they have some buoyancy trouble, floating, difficulty getting down and staying upright. But they snap out of it and recover. Then they start "whirling" and having spaztic episodes that end with them looking dead on the bottom......then they snap out of it, right themselves and are "OK" till the next one.

I move them to quarantine once they are being spaztic, bare bottom with one plant and 75:25 new and tank water. Within 24 hours, usually overnight, the fish is dead and curled into a C shape. There are no signs of the body curling while the fish is alive or distress while in the quarantine.

Any insight on this?​

 

[Naughts]

spaztic episodes

Sounds like a parasite has effected the brain. It's good that you quarantine at first sight of the disease.

 

[JuiceBox52]

It does sound like a parasite or something else infecting the brain.

 

[jesusjones]

Thanks for the feedback, I will keep an eye on the rest of them. Hopefully they continue to do well.

 

[jesusjones]

Merry Christmas and good news!

The cories seemed to be getting worse. One bigger one looked faded and a smaller one wasn't eating. There was (more than I realized) tree bark (nitrogen) shedding off a piece of wood and mixing into the sand. I decided to vacuum out the random sand and replace it with a finer pool filter sand, changing around 2/3 of the water at the same time.

The cories schooled and are eating together within 2 hours of the change. This morning they look even better, seems promising

​