Wjats wrong with my cory(Pic inside)

[thegame2024]

I was wondering whats wrong with my peppered cory cat... he rests on the top of the surface or lodges himself into things... he swims with the others but he does this usually at night... I keep thinking hes dead. Could it be swim bladder? He can stay on the bottom but not rest there. Heres a pic of what he does... its kinda blurry

[fishlore101]

My pleco does the same thing. He will stay at the water line or wedge himself between the heater and the glass, but will swim back to his cave. I don't think it is swim bladder because it sounds like he swims normal with the other fish. Test the water to see if everything is normal, and keep an eye on the other fish.