As said above, the Sleeper Goby will make a mess! Please do not buy one if it will end up annoying you...I hear of people all the time "getting rid" of them because they spread sand around a lot. Not really fair since its just natural to them. I love mine, he keeps the sand very clean and its not a big deal to me if he makes a bit of a mess
This is an example of him cleaning the sand:
