The German Wolfgang Eysel has under aquarium conditions observed differences in the nest-building of Xenotilapia melanogenys; apparently individuals from the northern populations in Burundi construct nests with a inner spawning pit, while individuals from the southern populations from Zambia construct nests without an inner spawning pit (Eysel 1990).
Konings mentions no differences in the construction of the nests throughout the Lake, stating that all populations of Xenotilapia melanogenys construct equally shaped nests with an inner spawning pit (Konings 1998), but a recent publication depicts a male from Kantalamba, located in the southern part of Tanzania, in a nest shaped like a wheel, with thin rows of sand spreading out from the inner pit to the edge of the saucer-shaped nest (Konings 2005).
Eysel´s observations were done in the aquarium and some reservation should of course be taken because of this, but it could be interesting to see if these observations are just a coincidence or if there really are differences in the construction of nests, that could be related to different geographical populations of Xenotilapia melanogenys.
Xenotilapia melanogenys male from Nyanza Lac in the aquarium of Julien Ruiz; France. The males of X. melanogenys normally shows one or several black spots in the dorsal fin – are the number and position of these spots an expression of different geographical variants or do they differ within populations? Photo by Julien Ruiz. Determiner Thomas Andersen.
The males of Xenotilapia melanogenys are normally thought to show very little geographical variation throughout this species distributional range. The males are normally adorned with one or several black spots in the dorsal fin and whose position varies a lot – are the number and position of these spots an expression of different geographical variants or do they differ among males within the same population?
A discussion of this topic can be found in the Cichlid Room Companion Forum.