I bought a diamond goby about 2 weeks ago to clean my sand up. He did a great job, had it spotless in less then a week. Last week I went out of town for a few days. When I got back, I did not see the goby, I though he was just hiding in his burro. After the 2nd day, I started looking a little harder, and feared that he jumped. My stand is kind of unique in that the tank is completely encased in the stand/canopy. The stand and canopy are connected in the back to hide all of the plumbing. There are only 2 spots he could jump out of the water at and he found one of them. I was planing on covering those 2 spots with screen, but did not get to it before I went out of town. I didn't think it would be an issue either because I never saw the goby leave the surface of the sand.