I agree with Jon, there are a few hundred cichlid species from Central America, and many hundreds from South America, and one size does "not fit all.
You need to be more specific as to your preferences, to get an educated answer.
Many new world cichlids are territorial. If you pick one of those species you may only be able to put a pair or trio in that size tank because territory often is based on footprint, not height.
If you choose a shoaling type species, your options get looser.
In a tall tank you could put a territorial pair of cichlids, and then lots of shoaling/schooling non-cichlid dither type fish the live nearer the surface.
Like the ones in the video from a Cenote in Mexico.
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