I keep open tops and I've only had one fish jump, my female betta. But it was while feeding and she tends to get a little over excited. She was fine, if a little shocked lol
I would also suggest that a fish will jump for a reason. That could be food or it could be water quality / tank conditions or even bullying / territory disputes.
The Labyrintfamily have a different system breathingsystem. They go to the surface of the tank every 2 or 3 minutes to inhale air. The air above your tank should have the same temperature as your water, otherwise they will get sick. The air above an open tank is most likely to be very different (temperature) then your watertemp. So Labyrintfish like goerami's are better of in a hooded tank