Do you drill air holes into your topless tubs in a rack?

i used a spacer of 3/16 between each level but i am not sure if i should still add air holes. What do yall think?

If you've got a 3/16" gap between the tub and the next shelf, I wouldn't worry about adding any holes.

Yup, that plenty of air.

i thought so :) also, what kinds of stopper are using to keep the snakes from a possible escape?

I don't use any stoppers.