First record and evidence of an established population of the darter goby (Ctenogobius boleosoma) in the Adriatic Sea

Abstract

Non-native species represent one of the major threats to the preservation of Mediterranean biodiversity, as asignificant number of marine organisms colonize this region either by passing through the Suez Canal or via other vectors, such as marine traffic and ballast water. Fourteen non-native goby species have already been documented in the Mediterranean Sea, with their distribution currently being restricted to the Levantine Basin and Aegean Sea, in addition to a single record from the Ionian Sea. In contrast, no non-native species from this group have been recorded in the Adriatic Sea to date. This study documents both the first record and evidence of an established population of the darter goby (Ctenogobius boleosoma) in the southeastern Adriatic Sea (Montenegro), identified by genus and species diagnosis. Thirteen individuals were collected from the Jaz River between September and December 2025. The fin coloration pattern is described, including the unusual pectoral fin coloration for this species.