I don't keep the mealies or waxies in the fridge, the waxies die and the mealies don't eat and grow, which is what I want. Both seem to die quicker if kept too cold since the recommended temp for them to be at is between 45-55, and our refrigerators are much colder than that.

I buy 1000 crix at a time, .5" ones, and let them eat and grow while I'm using them so they are nice and healthy when I feed them.