Fish catch composition in 21 gill net samplings performed between 2014 and 2015 at Rhodes Island (Aegean Sea, Greece) was analysed, with the aim to contribute in filling scattered information on coastal fish assemblages in a Mediterranean region heavily impacted by biological invasions. A total biomass of 183 kg was collected comprising 1070 fish individuals, distributed along 43 native and six Lessepsian migrant species. The alien Siganus luridus prevailed in terms of frequency of occurrence, followed by the native Sparisoma cretense, which exhibited the higher abundance and biomass, followed by S. luridus, Scorpaena scrofa and Siganus rivulatus. Ratios between alien and native species as well as between their abundance and biomass are discussed.

This record represents the northernmost occurrence of Lessepsian migrant fish Siganus luridus in the Aegean Sea. A single specimen was caught off the coast of Assos, Edremit Bay, in November 2014 by trammel net at a depth of about 2–3 m on a sandy, rocky bottom mixed with Posidonia. Here, the morphometric and meristic characteristics of the specimen are identified and the dispersion of the species in the Mediterranean Sea is briefly discussed.

The Red Sea goatfish, Parupeneus forsskali, was collected for the first time off the Mediterranean coast of Israel. This finding, in addition to another specimen reported recently from Lebanon and numerous observations by underwater divers, strongly suggests that this species has established a population in the eastern Mediterranean.

The spotted halfbeak Hemiramphus far (Osteichthes: Hemiramphidae) is recorded from Collo Bay (eastern Algeria), representing the second report of this species in the western basin of the Mediterranean Sea. The two specimens measured 25.9 and 29 cm total length and were captured by fishermen in December 2010. Morphometric characteristics are described. This species is the second lessepsian migrant fish reported from Algeria and the third one to be found in the western basin of the Mediterranean. The spread of the species through the Sicilian Channel is discussed.

A specimen of the Indo-Pacific blacktip grouper was collected at a depth of 20 m from off the coast of Lebanon. This constitutes the first record of the species in the Mediterranean and adds to the number of exotic serranids in the Mediterranean Sea.

The variability of shell morphology and relative growth of the invasive pearl oyster Pinctada radiata was studied within and among ten populations from coastal Tunisia using discriminant tests. Therefore, 12 morphological characters were examined and 34 metric and weight ratios were defined. In addition to the classic morphological characters, populations were compared by the thickness of the nacreous layer. Results of Duncan's multiple comparison test showed that the most discriminative ratios were the width of nacreous layer of right valve to the inflation of shell, the hinge line length to the maximum width of shell and the nacre thickness to the maximum width of shell. The analysis of variance revealed an important inter-population morphological variability. Both multidimensional scaling analysis and the squared Mahalanobis distances (D2) of metric ratios divided Tunisian P. radiata populations into four biogeographical groupings: the north coast (La Marsa); harbours (Hammamet, Monastir and Zarzis); the Gulf of Gabès (Sfax, Kerkennah Island, Maharès, Skhira and Djerba) and the intertidal area (Ajim). However, the Kerkennah Island population was discriminated by the squared Mahalanobis distances (D2) of weight ratios in an isolated group suggesting particular trophic conditions in this area. The allometric study revealed high linear correlation between shell morphological characters and differences in allometric growth among P. radiata populations. Unlike the morphological discrimination, allometric differentiation shows no clear geographical distinction. This study revealed that the pearl oyster P. radiata exhibited considerable phenotypic plasticity related to differences of environmental and/or ecological conditions along Tunisian coasts and highlighted the discriminative character of the nacreous layer thickness parameter.

Between October and November 2010, several individuals of Fistularia commersonii, a lessepsian species, were fished by trammel nets in less than two weeks along the French coast in the north-western Mediterranean. These catches represent the most important records of the species in the western basin of the Mediterranean to date, specifically in areas where the species has rarely been observed before. This paper synthesizes the records of F. commersonii along the French coast starting from the first record in November 2007 until the most recent reports, and discusses the present status of the species in the north-western Mediterranean Sea.

The lessepsian migrant fish Decapterus russelli was recorded for the first time on the coast of Turkey, north-eastern Mediterranean. A sampling campaign was carried out from January 2008 to March 2010. A total of sixty-seven specimens was caught with trawl nets at a depth of 15–18 m. Decapterus russelli was found in Iskenderun Bay on 17 October 2009, Mersin Bay and Erdemli Bay on 17, 18 and 23 March 2010. Some morphometric and meristic characteristics of this species are presented here.

The first finding of the alien crab Atergatis roseus (Xanthidae) in Rhodes Island (Hellenic south-eastern Aegean Sea) is documented, increasing to eleven the number of alien brachyurans present in the area, nine of them having Indo-Pacific origin. Due to its coloration, not in accordance with the literature, the specimen is described in detail.

The lessepsian species, Upeneus pori (Pisces), Sepioteuthis lessoniana (Cephalopoda) and Aquilonastra burtoni (Echinodermata) are reported for the first time from Cyprus, while the lessepsian bivalve, Barbatia plicata is reported for the first time from Kastelorizo Island, Greece. Finally, the fish species Pempheris vanicolensis, Sphyraena pinguis and Hemirampus far were collected more northerly than their previous records in the Aegean Sea. The geographical distribution of these species is given. According to the new records, the number of lessepsian fish, mollusc and echinoderm species known from Cyprus increases to 25, 38 and 4 species respectively.

Some adult specimens of the bluespotted cornetfish, Fistularia commersonii (Osteichthyes: Fistulariidae), are recorded for the first time along the Algerian coasts, in Skikda Bay (eastern Algeria) and offshore Bou Ismaïl Bay (central Algeria). More than 100 fish measuring from 73 to 88 cm were captured by fishermen. A sample of three specimens is described here. This species is the first lessepsian immigrant fish in Algeria, indicating its fast spreading ability and its success in the Mediterranean environments.

A specimen of the Indo-Pacific parrotfish Scarus ghobban has been reported from the Mediterranean Sea. The fish, the second one from the Mediterranean, was speared off the shore of Beirut (Lebanon) in November 2004. Morphometric measurements and meristic traits are provided and the presence of the species in the Mediterranean since 1999 is discussed.