In comparison with the species flocks of lakes Malawi and Victoria, the taxonomy of the estimated 250 species of Lake Tanganyika cichlids is relatively well known. It has only recently become clear that many of these species show a considerable amount of geographical variation in general morphology. The genus Tropheus, Boulenger, 1898, consist of highly stenotypic rock dwellers whose limited capacity for dispersal gave rise to over a hundred colour morphs. Notwithstanding their high chromatic and genetic differentiation, their morphology is assumed to have remained static. In this study, we investigated interpopulational morphological differentiation in Tropheus duboisi, Marlier, 1959. As this basal species shows only minor colour differences and is less stenotypic then its congeners, it is ideally situated to test the hypothesis of morphological stasis in Tropheus.