One gallon, One Clown.

Just some live rock won't be very intresting at all... but you could if you wanted. If you can keep the parameters stable enough, then you could also keep some soft corals.
 
Yeah, that has to be a temporary setup. I have 2 oscellaris clowns and they love the current and swimming room. Putting them in a 1 gal tank for any amount of time would be an injustice.
 
For someone like me who had never had a reef tank I was absolutely inthralled by my one gallon of water with some live rock in it. I spent alot of time with a magnifying glass watching as things started popping up and growwing out of the rock. Then again I have always been drawn to microcosms. (dwarf cichlids, pico reefs, spiders)

I grew up with the idea that saltwater was so difficult (and back then it was), but with the availability of good quality liverock, compact flourescent lighting, and miniature pumps I have not found it to be nearly as daunting as it was made out to be.
 
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