Healthy Clownfish suddenly acting weird

[Tinfoil_Anemone]

Hey guys and gals, so I'm completely bewildered as to what to do about the situation of my male clownfish. He has been fine for weeks being very active and eating aggressively.... last week I turned in my lights for the first time. Both him and the female responded well to it and have been doing great. Then! Suddenly today I look into the aquarium and I see this (reference picture)... he's listless stuck to the overflow, I would say breathing heavily. Like he is about to die I quickly tuned the lights off as there are no corals or anything to help with whatever was stressing him out and he instantly pops off of the overflow and starts swimming around fine.. I turn them on and back he goes In to seizure mode listless and breathing fast. It like the lights are suddenly causing this??? ALL perameters are spot on. No maintenance in the last 3 days, nothing has changed. I don't know what to do or how to deal with him its the strangest behaviour... sometimes but rarely he's been doing it with the lights off.. please help with some knowledge.

Ammonia: undetectable
Nitrites: undetectable
Nitrates < 1
Phosphates: 0.01
Calcium: 400 ish
Magnesium: don't check at this point
Alkalinity: 10.2
PH: 8.4

 

[Tinfoil_Anemone]

Sorry guys this is a duplicate thread.. I don't know why my phone did it twice.. if there are any suggestions to take it off let me know thanks..