“Black Acara” was a common name for Cichlasoma. They were also called “Port Cichlids.” This is a group of similar-looking species of Cichlasoma that are identified by location, number of hard spines in the anal fin, presence/lack of scales in the dorsal and anal fin bases, etc.
The most common and widespread seems to be C. amazonarum. Then you have the southernmost species with pretty green and blue iridescence, C. dimerus. C. bimaculatum is the official “black acara” if memory serves me correctly, but they are more drab and brown than the ones in your photos. C. portalegrense was the “port acara/cichlid” and at one point I think they were all considered that species, but their range is now considered much more restricted and other species have been described. So using that common name is a bit confusing now.
IMO yours look like amazonarum but you’d need good shots of their anal fins extended so you could count the spines and also see if the scales overlap into the base of the fins.
The best people to ask about Cichlasoma IMO are D dogofwar Mahlerfan and Ken Davis, but I don’t know if any of them still post here.
The most common and widespread seems to be C. amazonarum. Then you have the southernmost species with pretty green and blue iridescence, C. dimerus. C. bimaculatum is the official “black acara” if memory serves me correctly, but they are more drab and brown than the ones in your photos. C. portalegrense was the “port acara/cichlid” and at one point I think they were all considered that species, but their range is now considered much more restricted and other species have been described. So using that common name is a bit confusing now.
IMO yours look like amazonarum but you’d need good shots of their anal fins extended so you could count the spines and also see if the scales overlap into the base of the fins.
The best people to ask about Cichlasoma IMO are D dogofwar Mahlerfan and Ken Davis, but I don’t know if any of them still post here.