Be safe and put a screen lid on there. You don't have to clip it, but have it. Trust me, mice can leap a lot further and higher than most people expect.

Better yet, save more money and back pain and put the mice in tubs with screen on the top sides and lids. Again, trust me...cleaning of mice is an every few days thing, and with a massive tank you'll be hurtin. I keep my breeder trios and litters in 26"x15"x10" tubs and the weaned adults in slightly smaller ones.



You could even build a small rack setup if you wanted to. There are plenty of threads here that detail the building of such things. I just like giving my mice more room and toys and such.