Black-faced blenny 2007) and "T. tripteronotum" (Risso, 1810). Besides "T. delaisi", all species are endemic to the Mediterranean Sea. The species "T. delaisi" is subdivided in two subspecies: "T. delaisi delaisi" in the Mediterranean Sea and "T. delaisi xanthosoma" in the Atlantic Ocean. The subspecies can be distinguished by their courtship behaviour: "T. delaisi delaisi" court in free water and "T. delaisi xanthosoma" stay on the ground for courtship behaviour. The speciation process is still under discussion and several hypotheses have been proposed. Black-faced blenny The black-faced blenny ("Tripterygion delaisi") is a small benthic fish from the family Tripterygiidae (triplefin-blennies). It occurs
Round goby Nord-Ostsee (Kiel) Canal. As of 2010, the westernmost site of round goby occurrence in Europe was the Lower River Scheldt, the tidal zone in the river mouth, and Albert Canal, Belgium. In 2011, the round goby began invading the fresh waters of France: the species appeared in the Rhine River (on the border between France and Germany), and in the French part of the Moselle River. In total, 52 parasite species are registered in the round goby in the native area. Most abundant parasites of the Black-Sea round goby are metacercariae of trematodes of Heterophyidae family, such as "Cryptocotyle concavum",