Allmänt

Fully man created from old aquarium lines that were called Hemichromis bimaculates (wrong name) at that time. They were probably hybrids already. You select the more blue ones and start line-breeding for blue. Mother to son or Father with daughter. Do this several times and the by selecting the blue increases. Just like modern fancy guppy or your chiwawa. You will never find the original species in these cases.
Anton Lamboj gave a talk on the genus and showed a diagram of relationship based upon DNA analysis, and he included a sample from this tank strain. It placed squarely in the H. guttatus group, so most likely a line-bred color of that species.

Litteratur

Anton Lamboj & Stephan Koblmüller (2022) "Molecular phylogeny and taxonomic revision of the cichlid genus Hemichromis (Teleostei, Cichliformes, Cichlidae), with description of a new genus and revalidation of H. angolensis". Hydrobiologia. DOI: 10.1007/s10750-022-05060-y