Originally Posted by iDreamInSaltwater
small gobies are your best bet, neon blue, or clown gobies like pat suggested, theyre fun little guys and usually low maintenance
I'm going to have to disagree on your last point.
As I'm sure you know or will find out, nothing about a nano reef is low-maintenance. A lot of smaller fish are very picky and docile eaters who are easily startled. Make sure no matter what fish you buy, you make sure they are eating and fat at your LFS
. It is not uncommon for clown gobies to "reset" when they are moved from tank to tank, they may stop eating and hide for several days even if they are super healthy and must be enticed to eat again before they return to the state your purchased them in.
After the initial concerns though, most smaller species prove to be fairly hardy if you keep up with conditions.