While I consider myself reasonably observant, it never occurred to me until recently how different the inhabitants of a cichlid community tank behave when the tank lights are off versus on. My 75g tank houses eight different species of Tanganyikans, 17 cichlids total. If you follow the blog, you know that my focus is on what would largely be labeled as dwarf cichlids.
The largest occupants are the three A. calvus and a hefty N. tretocephalus. While my experience with both Malawi and Tanganyikan cichlids suggests Tangs are more docile in a community setting, don't be fooled by their calmer demeanor. They have an equal capacity for aggression and destruction as the Malawis. However, when the tanks lights are out, calm seems to prevail. I'm not talking about night time, complete darkness. I'm talking about ambient light and no tank light on.
My Malawis are pretty calm when the lights are out as well, but in my experience, it's when the lights are out that bad things happen in the Malawi tanks. I agree I probably have a too small of sample size to make a general statement, but my experience suggests that a mildly stocked, mid-size Tanganyikan community tank containing dwarves is a mostly docile proposition, especially with the lights out.
The Cichlid Room Companion
Tropical Fish Hobbyist
American Cichlid Assoc.
African Cichlid Hub