They only sift the surface trying to get algae. They never "dig" per se. Others do dirt and goldfish. I have never heard of anyone having their dirt dug up. Sorry, but this is the best I can do for pics right now. My crappy cell cam won't take a full tank shot with enough detail to show anything. The tank is still pretty bare anyway. My next step will be to mass plant a bunch of fast growing nitrate eating plants like water violet, water sprite, water hyacynth, Jungle vals, elodea...you know. I want to plant so many the growth will outpace the fish eating it. I want them to eat the plants. Two birds, one stone, you know.