The big-scale sand smelt (Atherina boyeri) is a species of fish in the Atherinidae family.It is a euryhaline amphidromous fish, up to 20 cm in length. In the video we met them snorkeling in the summer between swimmers, in apnea during the end of a storm in autumn. These fish are easy to meet practically all year round and let themselves be approached by the diver who is not a threat to them.
It is a small pelagic fish species which occurs near the surface in the littoral estuarine zone: in lagoons, salt marshes (77 psu), shallow brackish areas (2 psu) and inland waters which are rather unsuitable for other fish species, due to their high ionic strength and salinity.
Body is rather long, slender, moderately flattened. Eyes are large. Head and body are scaly. Mouth is protractible, upwardly directed, with small teeth. Lower jaw has an upper expansion within mouth (high dentary bone). There are two separate dorsal fins, with all rays of first and 1-2 anterior rays of second dorsal fin being unsegmented. The anal fin is similar to the second dorsal fin, while the caudal fin is forked. The first dorsal fin has 6-10 flexible spines.
It is found in the eastern Atlantic from Portugal and Spain to Nouadhibou (Mauritania) and Madeira. Also it occurs in the Mediterranean, including the inshore lagoons, such as Trasimeno and Lesina in Italy, Hyèresin the southern France such as Marseille and Lake Qarun in Egypt; an isolated population is found near the coasts of England and the Netherlands. In the Black Sea, it is widespread along all coasts, in lagoons and estuaries, in the downstreams of rivers Danube, Dniester, Southern Bug, Inhulets, and Dnieper, with a permanent population is in the Kakhovka Reservoir.