The diversity of color patterns among killifish species is incredible and unique (greater than coral fishes!), as a mirror of their genetic diversity.
As an example, photos of several populations of the African Aphyosemion bualanum or Nothobranchius kafuensis are presented in the small gallery, on top.
A reason why aquarium populations must be named (usually, after the place of origin) and separated to avoid hybrids that are fully sterile. For example, Aphyosemion bitaeniatum - Lagos (the population was collected near Lagos, the city of Nigeria, Africa)
Therefore the options are nearly infinite: the 1100+ valid species turn out into more than 4000 aquarium populations !
Color pattern and Morphological diversity:
Pattern variability between 2 species of the same genus, e.g. Nothobranchius.
Note the differences in the respective insertion of Dorsal and Anal fins (jubbi, ex-neumanni, advanced ; elongatus, moved backwards) :
Pattern variability within a species, e.g., Aphyosemion bualanum:
Pattern variability on Nothobranchius kafuensis:
Blue phase and Yellow phase of a single species:
Fundulopanchax gardneri mamfensis:
Discover more on Killies?