just do one male and one female guppy or danio or minnow and watch the numbers grow. Always wanted to, never had the patience. Though sorta of trying with a 20g right now. **** you said no livebearers.
Heavily planted? or will it? good group of sparkling gourami and a bunch of otos. Or just a couple gourami of your choosing. I would do Sparkling, Pearl, or Honey. Heard Liquorish Gourami are neat too. The opal, three-spot and golds tend to get aggressive once they get to breeding ages. The Pearls will too but it's more mellow.