Yes i reckon you could.You could have 2 notho species 1 would have to be guentheri gold and maybe one of the other 3 sp we have as all the of these females look the same.You could also have gardneri gold,blue and albino easly told apart.Both australes choc and gold easly told apart and sjo's.The only thing is that sjo's will eat everything aprt frm the gardneri.If you wanted a tank with nice colour you could have a few pairs of Aphyosemions eg bitaeniatum,australe and maybe a gardneri sp but they can be aggressive.So yes you can have a tank mixed with killies just got to choose the rite ones.
cheers Kyle