Have you put your fronts in yet? If not then i would like to add some of my opinions. In that type of tank you can have 4 fronts in there, assuming that they are still fry's or around the 3-4" range. Just note that they will eventually grow up to 12-15" in size when they reach full adulthood. If you would like to add other species then i would like to recommend some small clown loaches, they look great with fronts and has great contrast! They will get a long fine. As for substrate and decor, use sand and rocks and create hiding spaces. They will eventually spawn if given the right atmosphere and habitat.