An updated inventory of alien marine fauna in coastal and offshore Tunisian waters is presented. Records were compiled from scientiic and 'grey' publications, presentations at scientiic meetings, theses presented in fulillment of requirements towards MSc and PhD degrees, websites and personal observations. 136 alien species were recorded in Tunisian waters, 60 records in northern coasts, west Mediterranean and 76 in central and southern coasts, central Mediterranean. Nearly half of the first sightings in Tunisian waters took place in the Gulf of Gabes. The dominant taxa are Crustancea (24%), Mollusca (23%), fishes (19%) and Annelida (13%). Twenty-one species previously reported as aliens were, upon consideration, reclassiied as range-expanding Atlantic species. Amathia verticillata, previously considered native to the Mediterranean, is reclassiied as pseudoindigenous. Twenty-one alien species are newly recorded from Tunisia, including five ish species, five polychaetes, four crustaceans, four molluscs, and one each schyphozoan, bryozoan and tunicate. The indings of Gibberulus gibberulus albus, Morula aspera and Calcinus latens, three species new to the Mediterranean, and of Actaeodes tomentosus, reported for the second time in the basin, are described. Species were classiied according to their establishment status and their origins. This contribution highlights the dual origin of biological invasion in Tunisian waters (Red Sea and Atlantic), with slightly more species of Red Sea and Indo-Paciic origins (61.76 %). The impact of the alien species in Tunisian waters was discussed.
