This genetic (and possible morphological) study of Ameiurus nebulosus en A. melas aims to clear which of these species (or both) are present in Flanders and Wallonia. Historical literature mentions that both species were introduced in Belgium between 1880 – 1900. At this moment however it is believed that only A. nebulosus occurs in Flanders while recent literature only mentions A. melas to be present in Wallonia. It seems hard to believe that the distribution of both species is so region bound while both land parts have common river basins. So one would expect the same species or both species here. The same confusion exists with neighbouring countries France and the Netherlands, France has the black bullhead only and the Netherlands have both species although there exist no recent finds of A. melas. During the study Ameiurus specimens from Flanders, Wallonia, France, Germany, UK and the Netherlands will be sampled. Of each region/country 5 specimens will be genetically screened to find out which species are present where and already 30 whole specimens will be collected also for a possible future morphological study.