How do Diamond Gobies levitate rockwork.

[Larryr]

Over the years one of my favorite fish is keeping a pair of diamond gobies. I place a rock with a concave surface a thin layer of sand and have very good luck with them living under it. Each time I have noticed while the rock is about 2 inches thick and placed on the bottom with a sand bed that's maybe an inch deep on the overal floor they constantly move the sand and cover the rock. What baffles me is that over a few weeks the rock itself begins to rise up off the bottom. In my current setup it is about 2" higher off the bottom than when I put the gobies in 6 weeks ago. And that is with a very large/heavey flowerpot setting on top of the rock.

 

[JustAnotherNanoTank]

You know it’s kinda messing with me because my goby completely disappeared and I haven’t seen it. Last I saw it, it was making a burrow under a rock...