Ok, i've got a 12 gallon nano, so i may be able to shed some light here.
My specs:
Twelve gallon JBJ Nano cube deluxe
2 24 watt flourescent bulbs
1 200 GPH koralia powerhead
Also, one 150 gallon pump i nthe back
Filtration:
16 pounds LR in the main tank
2.5 pounds Live rock rubble in the filter section 2
Chaeto in the filter section 3
3 filter sponges in the first section (Rinsed out weekly with water changes to get rid of detritus)
Livestock:
1 True percula clown
1 firefish
1 Emerald Mythrax crab
3 Scarlet hermit crabs
3 Astrea snails
three featherdusters (Hitchhikers)
Bristleworms/brittlestars/copepods/amphipods/yada yada (hitchhikers)
Corals:
2 small colonies (10-13 polyps) of Zoanthid
3 Mushroom corals
1 small colony star coral (Hitchhiker)
Anywho, for a bit of advice.
Some will tell you the clown will be unhappy i nthe small space. However, thanks to my decent current, my clown's very happy. She just gets into the current and 'waddles' her way in it. I've never thought, for an instant, that the clown was unhappy. Eats well, active, flashes wonderful colors.
The firefish simply ikes to hover, so he too is happy.
However, keep in mind that i have more than double your liverock, so double your biological filtration. With your low amount, i'd say one clown or firefish might be pushing it...
Buit, then again, i want my water param's as close to perfect as possible. Corals and all.
If you have any other questions ,feel free to PM me. Granted, i'm still fairly new to this myself, but I do read alot, and being i was there but a few short months ago, i might be able to offer some pointers.