Heh. I tried feeding Roo and Vash in separate tanks, they just looked at me funny like "Oh my god, where's my tree?!?! I want my box back! Why is it so white in here? Where did my box go? MOOOOOOMMMMMM!!!!!!"
After that, I just let them eat in their tanks. I check daily for waste but my substrate doesn't hide much in the way of poopies/pee nuggets.