A trio (1 male, 2 females) would work. You could equaly go for a single male. it's best to avoid pairs - especialy in smaller tanks - as the male will harass the female and, with only one, there will not be any division of the aggression.
Because of the tank's size, there are only a few fish that would work. I'll find you a link to a post I made a while ago ont eh subject of stocking small tanks but, what I'd personaly reccomend is some pygmy cories (a small school of 4). They are very active fish and double as both mid and bottom-dwelling catfish as they spend a lot more time swimming in the mid layers than is usual for cory catfish. They can be difficult to find but most LFSs can order them in or you can buy some online. As these only get to about 1", you'd have just enough room for maybe a small mid-dwelling fish like some endler's livebearers (or some male guppies). It's best to stick with only males because you can't afford to have fry survive in that size tank but that also means you need a minnimum of 4 to keep aggression under control (more so in guppies than in endler's). Males are, however, luckily, smaller than females - only about 1", less for endler's. With the guppy option, I'd reccomend fish that don't have long delta tails. The hybrid sword-tailed guppies and single-sword guppies are a better option and also stay smaller (these are typicaly guppy X endler's but it's best to reffer to them as 'guppies' as, idealy, hybridizing endler's should be discouraged).
In total I am suggesting 4 pygmy cories, 4 male guppies/endler's and a trio of honey gouramies. A tank like this would look great with a sand substrate and live plants.
Here's that link i mentioned:
http
/www.fishforums.net/index.php?showto...116208&st=0