Haplochromis cyaneus was previously known as Haplochromis sp. "blue rockpicker". It was described as Haplochromis cyaneus in 1998 by Seehausen, Bouton & Zwennes. It has been found in rocky habitats from Sengerema region (Chamagati) to Speke Gulf (Nanzio, Makobe) with a very scattered distribution; it lives in waters from 1 m to 6 m deep slightly offshore from gentle to very gentle slopes with small to very small boulders. The major part of its diet is composed of blue green algae and to a lesser extent insect larvae. It lives in sympatry with H. flavus (yellow rockpicker) but its diet varies slightly (more algae) and in all the habitats, it's more abundant than the yellow sibling species H. flavus. It shares its habitat with many others algae scrapers of the Neochromis, Mbipia species but also some others species such as H. sp. "short snout scraper", H. sauvagei. We have here a very rare species being found at only three localities in the eastern part of the lake. Its bright blue coloration with vivid red fins makes it a truly beautiful fish to keep.