I have been keeping about 300 medium dubias over the last week as feeders for my beardie. But for some reason everyday as I pull some out to feed my beardie I notice a few dead on their backs. I have the dubias set up in a 20 gallon which I keep in a closet and I make sure they have food and water crystals daily. I’m losing about 3-5 dubias a day. What am I doing wrong?