It is possible that the large meal increased his oxygen needs. Keep the water low until he seems better. After that you're probably fine to raise it. As far as I know as long as you have enough water movement and turnover there doesn't need to be surface agitation in a properly stocked tank. Surface agitation definitely helps but I don't believe it's necessary in most situations.
It is absurd to talk of one animal being higher than another. We consider those, when the cerebral structure/intellectual faculties most developed, as highest. A bee doubtless would when the instincts were.