Bellotti's goby
Gobius ater, Bellotti's goby, is a species of goby native to the Mediterranean Sea from the Balearic Islands and the Gulf of Lion to Nice and Sardinia. It occurs in shallow waters and lagoons where it prefers beds of the seagrass Posidonia oceanica. This species can reach a length of  SL. References 

Gobius
Fauna of the Balearic Islands
Fauna of Corsica
Fauna of Sardinia
Fauna of Sicily
Fish of the Mediterranean Sea
Fish of the Adriatic Sea
Fish described in 1888