Starting from the hypothesis that rock-dwelling cichlid species are more constrained in their dispersion by physical barriers and thus display more structured populations than sand-dwelling species, the degree of population substructuring, inbreeding and regional differentiation among four sympatric Copidachromis spe- cies from Lake Malawi is examined. A multidisciplinary approach is used, including micro-satellite loci analyses, morphometric analyses, life-history traits studies, stomach content analyses and stable isotope analyses on the population level. An improved in the dispersion capacity and the geographic patterns of gene flow in these species is expected. New insights in the relation- ship between genetic variability and phenotypic plasticity and the role of assortative mating are expected.