On some of those things it's more enlightening to distinguish between genera and species, or habitat and niche, than continents. There's as much or more difference in communication cues between discus and green terrors or frontosa and mbuna as there is Malawi and Amazon.
For example, on the mouth opening and gill flaring vs fin flaring and side display thing-- Cyphotilapia (Lake Tanganyika) do the former,
not the latter, while they fight by locking mouths. Not only that, but while Malawi cichlids extend their fins in aggression mode, Cyphotilapia close them in preparation for a fight. That, and a lot of why you don't see territories in a typical Malawi tank is because they're typically overstocked to mitigate aggression, precisely to try and prevent territories. So, for example, a number of mbuna species claim and fiercely protect small, individual territories in their natural, rocky habitat. I've seen mbuna tanks set up this way, filled with rocks with a lot of gaps and holes and each fish happily tucked into their particular spot without much drama. Tanganyikan shell dwellers have a different version of this, using shells instead of holes in the rocks.
Meanwhile, you absolutely don't want to crowd some of the medium to larger Lake Tanganyika cichlids, like Cyphotilapia, Cyathopharynx or Benthochromis. You'd want to keep them more like large new world cichlids, with plenty of space. Cyathopharynx, for example, shoal in shallow water, while males build and protect large nests in the sand to attract females and breed, Cyphotilapia gibberosa hang in small groups near rocky shelfs and boulders, while Benthochromis are shoaling, open water fish. Body language for some species can be quite unique, for example the "bugling" of Benthochromis. Whether a species establishes hierarchies depends mainly on whether they're shoaling or social vs solitary, not which continent they come from. Feeding strategy is another factor in social structure, lurking predators vs traveling predators vs foragers vs grazers.
Bottom line is a lot of the generalizations between continents that I've heard over the years don't really hold water, including that SA fish are low pH, soft water fish while African cichlids like "liquid concrete." Tell that to some of the riverine African fish or an Andinoacara stalsbergi living in Laguna de Vegueta.
