[kenpau]

I have a 30 gallon shallow cube with the following stock list:

Pair of Percula Clownfish
Royal Gramma
Flame Angel

This seems to be a good combination for me with no aggression and plenty of movement in the tank. I am however struggling to raise nitrates and phosphates due to my filtration methods, so I have the following fish in quarantine waiting to be added:

female Lyretail Anthias
Springers Damselfish

I'd say 6 fish is the absolute limit for a 30G and even then it's a very delicate balance dependant on filtration and choice of fish to reduce aggression.