Do you think a Sunburst Anthias wpould be a candidate for a 12g Nanocube? You can't put much in them so it should be something nice as like these. It would only be 1 of these and a Hector's goby.
you still have to consider the amount of waste they will produce in a small area. it will make keeping the water parameters stable very difficult. at the least think of it this way. it is like you living in 1 room instead of a house, you would go nuts