there are lil gobys which can fit in a 3 that i've seen but i wouldn't recommend fish in anything less than a 10
no reason to push the limits of a fish's life
you shouldnt dare try these until you have enough experience, but dwarf sh can be kept in 1 gallons. also if this is ur first tank then you should know that smaller tanks are harder to keep the levels stable.
I saw a 1 gal at my lfs, with 3 corals/anemones, a teeny tiny clown, and one tiny cleaner shrimp. They wanted like $120 for everything complete with fish, etc.