I have an african cichlid tank and with the right stocking it can be a pretty neat tank to watch. Of course I have some aggression, a few of them have nipped fins, and I have one really dominant blue zebra (he is a lot brighter than the other males). My tank is 75g and its pretty crowded, but as other say, I think this is why I haven't have any deaths. Rather than having a dominant male with 3 fish to bully, he gets to choose between 18 other fish. The fish seem happy. THey are vibrant, they are breeding (i keep finding random babies) and its a really neat tank to watch.