The clingfish (Gobiesocidae) genus Gouania (Nardo 1833) is endemic to the Mediterranean Sea and inhabits, unlike any other vertebrate species in Europe, the harsh intertidal environment of gravel beaches. Following up on a previous phylogenetic study, we revise the diversity and taxonomy of this genus, by analysing a comprehensive set of morphological (meristics, morphometrics, micro computed tomography imaging), geographical and genetic (DNA‐barcoding) data. We provide descriptions of three new species, G. adriatica sp. nov., G. orientalis sp. nov., G. hofrichteri sp. nov. as well as re‐descriptions of G. willdenowi (Risso 1810) and G. pigra (Nardo 1827) and assign neotypes for the latter two species. In addition to elucidating the complex taxonomic situation of Gouania, we discuss the potential of this enigmatic clingfish genus for further ecological, evolutionary and biodiversity studies that might unravel even more diversity in this unique Mediterranean fish radiation.