Cory upside down but not dead?

[abrage22]

Woke up this morning to find one of my cories on top floating, I was going to net him to dispose it, but all of a sudden he started to splash around. He did that if anything would touch him.

The parameters are all good. The tank has been up for a few months now and was cycled in about couple weeks from old filter media.
It's a 20 long with 5 Cory, 4 cardinals, and 3 otos. All the cories last night were perfectly fine with no signs of illness. I do 40% water changes every single week.

Was this just a dud in the batch??

 

[LyndaB]

Corys can be somewhat sensitive, from my experience anyway. It's not that he's a "dud" but he could be the runt of the litter, so to speak.

It's definitely not a good sign that he was floating. You'll need to keep a sharp eye on this tank.

 

[Samzter]

Corys can be somewhat sensitive, from my experience anyway. It's not that he's a "dud" but he could be the runt of the litter, so to speak.

It's definitely not a good sign that he was floating. You'll need to keep a sharp eye on this tank.

I agree that doesn't sound too good at all. Hope it gets better soon

 

[2007PSanHa]

Swim bladder?