· Dichromatism = Usually sexual although not only. In sexual dichromatism the two sexes show different coloration. In some species (e.g. lake Malawi cichlids) the difference may be striking.
Those species that show only differences in coloration between the sexes are said to display sexual dichromatism, and others show no external characteristics that distinguish sex.
In sexually dimorphic species, the sexes can be easily distinguished by primary (shape of sex organs) and secondary differences (size, shape, color [sexual dichromatism], finnage).
It is rather difficult to tell the sexes apart in the Mayan cichlid, because there is minimal sexual dimorphism (shape) and dichromatism (color). However, among fish of the same age, the males tend to be a little bit larger than the females.
Although it doesn't show the kind of sexual dichromatism seen in African cichlids from the Rift Lakes, still the male is more colourful than the female. Dark gravel will bring out its spectacular coloration. Pairs usually swim side by side.
The different spot patterns may simply be population variation but might also be sexual dichromatism creeping in too, with larger, brighter spots on the males than on the females.
 See also: Species, Fish, Water, Aquarium, Cichlid
  
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