Yes, do not fill a reptile/amphibian tank with water; it will crack. Crickets will die in a refrigerator, it's too cold for them; but mealworms and night crawlers will be fine. Mealworms are fatty and have a hard exoskeleton that can cause impaction, which makes them a poor food. Too bad you are not a science major and could keep your crickets or some Dubia roaches in a lab. By the way; your 5 gal is barely adequate for 1 FBT; please don't get a second one in there .