I have one with my YWG, gone from about an inch to about 2"...vigorous digger, quiet citizen. This is a 54g tank with pep shrimp, crabs, small fishes: haven't lost any livestock to him in his 6 months in the tank. The YWG is my largest guy. I did put eggcrate down before building my rock pile, so my rocks are pretty solidly based. He makes a new burrow every few days.