How many guppies?

I'd try two, but you are going to need regular water changes and keep up with the tank well...
 
if you want cool tropical fish, maybe (mebs) you should try to get a larger tank.
 
I would go with 1 dwarf gourami and maybe 2 or 3 pygmy cories, panda cories, or otos. If you put 2 dwarf gourami's in a tank that small, one will most likely get bullyied(sp?) to death. The other fish are fine.
 
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