My tank is open topped when I am home (quite often as I work from home right beside the tank) and has a screen cover (window screen) when I am not and all night. I just put the screen on before i go out or to bed...its habit already. I had a puffer jump after owning him for 3 years a while back and vowed never to do open topped again. I did it again obviously
But I am trying to lessen the chance of anyone jumping.
It just takes one quick, little fight for it to happen and I am willing to bet if you have the tank set up for years, it will. Everytime. Just a matter of time. It took three years with that last tank.
So some days if I am out all day, the screen will stay on the tank and light will be blocked a bit but oh well...kind of like a cloudy day on the reef. Its window screen to keep bugs out so NO fish can fit through. Would even work for eels.
The nice thing was that you just buy the frame in length and cut them to fit the tank. Its super easy to make a quick custom cover. Takes maybe about 15 mins. max.
Good luck!
BTW, I had chalk bass in the past and they all jumped at some point either up into my canopy or would jump and hit the lights
Didn't do it often but over a few years, they all seemed to jump. Only 2 of the 6 died but still...if I didn't have a canopy, all of them would have.