Fish limit on BioCube 29? 4 or 5?

So I've got 4 fish in there now (2 OC clowns, 1 cardinal and 1 yellowtail damsel). Add in a few hermits and snails and an emerald, and no coral.



Is this already overstocked? Would 1 more (a royal gramma) be overstocked?



I intend to add some coral but not go full blown coral glass-to-glass. A couple pieces here and there.



Levels are all in line (except Magnesium which I'm raising, currently at 1075).



Thanks