I have only seen the true Aequidens rivulatus once about Fifteen years ago. This fish is a completely different animal. Aequidens rivulatus is a very aggressive fish hence the name Green Terror. On the contrary the Flametail is not aggressive compared to most Cichlids of that size. Males if kept in groups develop a large muchal hump similar to Amphilophus citrinellum .
Muchal humps are usually signs of dominance or an alpha fish in the tank.
You can only achieve a muchal hump if other males are present. This fish breeds in the typical Aequidens manner. They find a site in open water and usually spawn on a flat stone. Other Cichlids tend to hide their nest in caves, but Aequidens don't do this. The water parameter doesn't bother this fish.