around 4-6 months honestly I don’t remember but it’s been a while. And I didn’t turn it on rapidly but he’s fine now, it might’ve just been me not watching him sleep so intently beforeHow long have you had the clown ? To me it looks like unusual behavior and swimming almost upright is not normal.
Did you suddenly turn on the light to film ? If so you might have startled it, same as you would be if someone came in your room while you’re sleeping and stuck a flashlight in your face. The fish looks distressed.