You can pretty much keep your killifish with any fish that aint too small to fit in their mouth.... i have 3 golden wonder killies in my 29 gallon tank with 2 dwarf gouramis, 7 hareluquins, 3 black skirts, and other fish without any problems...
when i tried to add 11 neons the killi's went into attack mode and preyed on the neons until they all died :[