you should buy your own test kit and then youll know for sure, id be beyond shocked if that fish wasnt sick from something. laying/floating upside down is not a cute trick he is playing
I know why hes doing it. I saw him today he was nice and fine at the bottom of the tank and then i saw him swim up and take a gulp of air. then he started to float!! i think when he takes in air like other cories he takes in too much so the silly guy floats.