Y'know... Sororities are pretty hard. Sometimes you get a bunch who hate each other. I have TWO who don't, and they are still together (I need to move them x.x today!) because the others were beaten and removed -.-
Why not something different... I personally like Dwarf/Pearl Gouramis (I dunno if a 20 is ok?), I love leopard danios, balloon mollies, red wag platys and the really really colorful guppies =D I have ones with the tiger look, cheetah look, bright yellow and red... =D It's really up to you and what you would like :P
Breed for the breed, not for the money; the words any REAL breeder would understand.
You must know nothing in order to know all, for all is nothing and nothing is for all.