I have a relatively small tank and plan on upgrading soon. It's a 20g and I have a humu-humu in there along with some corals (and a few other fish). Everytime I do a water change (once a week) for the next day or two he'll pick the sand up in his mouth and throw it all over the place. He keeps putting it on top of some of my zoos and I'm wondering if it might be because he's stress or maybe it's normal. I move the sand off the zoos right away but with the other live rock he throws it on I clean it off when I do the water changes. It almost seems like he's doing it in spite of me. I know the tank is small for him but hopefully in the next few months I'll be upgrading to a 120g or so. Thanks for any help on this.