If you look at nature, you hardly ever find 2 cichlids of the same genus together, or two of the same feeding types. An d there are reasons for this, primary among them is 2 of the same genus, or 2 piscivores would be competing for the same resources. (there are some exceptions such as 2 shoaling species like Thorichthys) but this type are not what you are asking about, and these are social.
West of the Andes where Mesoheros festae are found they are basically the only cichlid of their iik, the other a Geophagus sand sifter.
Where N haitiensus are found, they are the only cichlid of its kind, there may have been more a million years ago, but it is theorized the less robust and equipped cichlid to adapt was made extinct by haitiensus
Where you do find communities of new world species, they often have different feeding strategies, that limit competition for resources.
For example in Lake Bacalar you find Vieja (omnivore with vegetarian tendencies) Thorichthys meeki (a sand sifter), Crytoheros spilurus (insectivore) Mayaheros uropthalmus (generized omnivore), and Trichromis salvini (predator).
If you tank is in the 1000 gal range you may get away with a couple, but small tanks in 100 to 200 range are seldom viable
Where I live and collect cichlids, in the Mamoni river, I have yet to find more that 3 species.
Darienheros calobrensis, a substrate picker that prefers rheophillic areas

Ithmoheros tuyrensus, an omnivore with vegetarian tendencies (similar to Vieja)

And Andinoacara coerleopunctatus, a generalize predator/omnivore that prefer more slack water areas.

notice how mouth shapes differ, which may help indicate to other cichlids of their trophic preference and non-competitive nature.
None also get that large, and I have kept them together, as a Mamoni river biotope, but adding another more aggressive cichlid than just he 3, would appear to me to be a mistake.
I did add a predatory Mamoni goby that at first ate all Mamoni tetras (dithers), grew some and then ate or killed Mamoni Plecos, grew some more, then started to selectively kill cichlids
I will not do that again.

Above the attempted community.
What I find best, are only single, or 2 species only tanks for Central American, and west of the Andes cichlids , and then only if they are very carefully selected.
