I kept a sleeper goby that I bought very small in my 72 successfully. The biggest requirements are a relatively deep live sandbed (1 - 3" in my humblest of opinions) and a very well aged tank. These guys love the 'pods
that live in the sand, and while some of them will eat frozen brine and the like, the majority of their day is spent sifting your substrate looking for chunks of yummy stuff. A refugium is pretty much a must have to keep 'em happy and well adjusted since that's where the crud they like to eat will be able to grow.