you shouldnt mix gourami species in a small tank like that, especially three spots and the like ( opaline, blue, gold, platinum... etc,) because some ofthem can get extremely agressive towards other male gouramis, even if they are not in the same species, and three spots and the like are also bully fish that are smaller than they are. its best to stick with the dwarf gourami and then the platies and guppies.