What makes you think swimbladder problem? Im my experience, swim bladder problems cause a fish to either sink or float, not spin around. Spinning usually comes in fish that are about to die from some bacterial or other disease. Is your tank otherwise "healthy?" (ie...good parameters, no new fish ...

Hi, can anyone please advise??

One of my cory sterbai's has lost colour around the head and is rolling over and over at the bottom of the tank.

He's pale and slightly red around the gills. Checked the water params -

Ammonia 0
Nitrite 0
Nitrate 8
pH 6.7
Temp 25
Substrate - small rounded gravel

I ...