I have an enclosed canopy on my tank, no glass top though. I'm not really sure what that is classed as so I didn't vote. I've still had fish jump out of the tiniest of holes (firefish can be very determined) and inevitably they find the eurobracing as well. Mostly I think they just ricochet off various hood parts back into the tank if they're interested in jumping. Although I found my royal gramma in the overflow the other day and there was no way he fit in between the overflow teeth, he's a rather portly looking fish
