JuanMi has muted audible commands. Apistogramma species are all dwarf cichlids from South America. Some species are smaller than others, but the average is three inches on a large male and two inches on a large female.
Most species are sexually mature at half that size though.
The female compensate out desire for pretty fish also, in that they have beautiful black on yellow breeding colors. Most are fond of soft acid water, but they are actually tolerant of a wide range of hardnesses. When water chemistry is the issue, pH is more important than hardness. I keep all my Apistos at a pH of 5.8-6.2. This is still high.