First records of the fish Abudefduf sexfasciatus (Lacepède, 1801) and Acanthurus sohal (Forsskål, 1775) in the Mediterranean Sea

To date, the Mediterranean Sea has been subjected to numerous non-indigenous species’ introductions raising the attention of scientists, managers, and media. Several introduction pathways contribute to these introduction, including Lessepsian migration via the Suez Canal, accounting for approximately 100 fish species, and intentional or non-intentional aquarium releases, accounting for at least 18 species introductions. In the context of the citizen science project of iSea “Is it alien to you?... Share it”, several citizens are engaged and regularly report observations of alien, rare or unknown marine species. The project aims to monitor the establishment and expansion of alien species in Greece. In this study, we present the first records of two popular high-valued aquarium species, the Scissortail Sergeant, Abudefduf sexfasciatus and the Sohal Surgeonfish, Acanthurus sohal, in along the Mediterranean coastline of Greece. The aggressive behaviour of the two species when in captivity, and the absence of records from areas close to the Suez Canal suggest that both observations are the result of aquarium intentional releases, rather than a Lessepsian migration.