If I have a pair of Julidochromis in a 30 gallon tank, could I add a few more cichlids to it to make a small cichlid community? (I do know that Julie pairs can be aggressive. My question is whether certain species will tolerate that aggression given the tank dimensions.) These are the species I'm considering: Labidochromis caeruleus, Aulonocara firefish, Pseudotropheus sosolofi and shell-dwellers. I don't expect to add them all but I'd like the tank to have as much variety as possible. I'd even be willing to settle for one Julie if it allows me to keep more species. The tank dimensions are 36 x 12 x 18 inches. Thanks in advance!