I went with a piece of plexi glass like everyone suggested for the lid to our new (used) 40 gallon tank for the 3 crabs we have (I know over kill)!!! My husband and I researched, I understand the crabs breath the wetness in the air. SO we only put 4 small holes for air circualtaion... Now the tank is warm enough, and the humitity is between 80 and 95 all the time.... Can that hurt them? Should I put more holes? I am so stress who new crabs would take so much energy...I am sure once we are all dialed in they will be easy and fun to watch and hold(sometimes) but right now feel a bit stressed.... They are alive so I have to do what is right by not killing them.... I am such a :dork2:..... :hahahaha: please let me know I would feel terrible if I drown them with to much humitity.