I feed animals in the tubs, but not in the tanks. George the black pastel did start launching himself at my hand every time I opened the tank. Cage aggression mostly only happens to me when there is thawing mouse smell in the air, but George is especially dumb. Or hungry! Or both. And for whatever reason he decided the tank opening meant it was meal time.

I use cardboard boxes. Shoe boxes when they were babies, old shipping boxes for adults.