Dime Sized Angel In Peril. Did I Gas My Fish?

[tetraodon_biocellatus]

One of my dime sized silver angels ive had for about a month is suddenly laying on his side at the bottom of the tank under my tiger lotus. He stands himself up for a moment and appears a listless, his breathing is pretty heavy. The others seem fine and there are no signs of distress with any other fish in the tank. I did a 25% water change and dialed back the pressurized CO2 which i feel could be a possible cause of his condition, the fish seemed fine last night, does anyone have any other ideas on what could be going on? Am i gassing my fish? I have no upped dosage within the past few weeks its been a consistent 1.5 bubbles per second (runs only when lights are on). Thanks.

 

[Munroco]

Sounds like swim bladder disease, when a fish loses its natural bouyancy. I'd look that up and if it fits maybe try one of the cures you find online. I've no experience of using CO2 so no ideas there.

 

[Bubbelzzz]

I'll guess it's not the CO2. If it is the CO2, at least some of the fish should be affected as well. Besides, it could be expected that too much CO2 would caus fish to swim near the surface. 
 
So I'll guess its a swim bladder issue.