Is this what you mean by a computer fan? And where do I put it? Her cage has the screen top and then the spot on top where you unlock the door has a bunch of air holes. Then the door alone swings open and when shut and locked it has spaces big enough on the sides and bottom for a small cricket to escape. That’s one reason why I won’t do the cockroach food. I don’t mind crickets here and there. But I can’t take the chance of a cockroach escape lol.