No, the glass top will not suffocate your frog. You have to leave a small space for air and excess heat to escape. If pacman frogs were easy to suffocate then they wouldn't bury themselves deep in the ground. I also wave my hand around in the tank when i open the top to spray or feed them. This circulates the old air out, and allows for more oxygen and fresh air to enter. they don't really like it cause the air feels cold like getting out of the shower.