Aphanius almiriensis, Kottelat, Barbieri & Stoumboudi, 2007

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 733-734

Aphanius almiriensis

Common name. Almiri killifish.

Diagnosis. Distinguished from Aphanius fasciatus by: ● female with dark, roundish blotches on flank, more or less connected by an irregular dark-grey midlateral stripe / ● dorsal and anal not reaching caudal base in male. Size up to about 38 mm SL.

Distribution. Aegean basin in Türkiye and Greece: Tuzla estuary, Lake Bafa and coastal lagoons around İzmir (Homa lagoon), springs near Almiri and Meligou ( Peloponnese) and coastal lagoons on islands of Lesbos and Kos and near cities of Thessaloniki and Kavala. Likely more widespread. Also at Palude del Capitano in Puglia, Italy.

Habitat. Slow-flowing streams, lagoons and lakes. In fresh and brackish water, up to 23 ‰ salinity.

Biology. Live up to 3 years, mature in a few months, usually late in year of birth. Males establish territories along banks, usually in dense vegetation but also between rocks, which they defend against rival males. Females spawn with one or more males, usually in algae or other vegetation near surface or in gravel beds. Few eggs are deposited in substrate during a spawning event. Individual females may produce several clutches in one day. Feeds mainly on algae and detritus and, to a lesser extent, on planktonic invertebrates and anflug.

Conservation status. LC.

Remarks. This species was considered restricted to two localities in Greece but appears widespread throughout the

Aegean basin. The distribution of A. almiriensis and A. fasciatus in the eastern Mediterranean is poorly understood, and a population from the island of Evia ( Greece) and possibly several others in Aegean belong to A. fasciatus . Both species may hybridise, but this has not been investigated. It cannot be completely excluded that the Italian population was accidentally introduced during Roman times, possibly from the island of Kos ( Greece).

Further reading. Kottelat et al. 2007 (description); Triantafyllidis et al. 2007 (distribution); Valdesalici et al. 2019 (distribution, first record in Italy); Saç et al. 2025 (biology).

When the Aegean was a lake. The biogeography of Aphanius is fascinating. Aphanius fasciatus is widely distributed throughout the Mediterranean, from Morocco to Syria and Egypt. The relatively shallow genetic differences between populations suggest gene exchange has occurred, likely facilitated by migration along the coast. However, the Aegean Sea has remained unimpacted by this migration, allowing A. almiriensis to evolve independently. The Northern Aegean region evolved as a restricted landlocked basin during the Miocene, with small temporary connections to the Paratethys (today’s Black Sea) and the Mediterranean. In the Tortonian (11.6–7.2 million years ago), the Aegean showed scattered lakes predominantly fed by local rivers and short-lived Paratethys connections. The first persisting marine conditions, alternating with brackish Paratethyan environments, indicate a late Maeotian age (6.9–6.1 million years ago) when the region formed a semi-isolated (Egemar) sea with multiple marine influxes. The cessation of marine conditions is well documented by a marked paleoenvironmental change to the brackish water environments, which correlates to the Maeotian/Pontian boundary (6.1 million years ago) in the Eastern Paratethys. During the Messinian Salinity Crisis (5.97–5.33 million years ago), the Northern Aegean was a brackish water system (Lake Egemar) that formed a passageway for Paratethyan overspill waters toward the Mediterranean. It is hypothesised that A. almiriensis had been isolated from the Mediterranean, A. fasciatus during these times, the latest during the Messinian Salinity Crisis. Nevertheless, while the isolation of the Aegean from the Mediterranean may have contributed to the isolation and speciation of both Aphanius , the last 5 million years should have been sufficient time for both species to invade each other’s ranges. The only documented instances of such an invasion are the records of A. fasciatus from Evia ( Greece) and A. almiriensis from Italy. Indeed, the dispersal ability of Aphanius appears to be relatively limited. Several molecular studies of A. fasciatus populations demonstrate a shallow but notable genetic structure within its large range. These studies indicate no rapid and unrestricted gene flow within the Mediterranean. The environmental factors limiting the recent distribution of A. fasciatus and A. almiriensis may have similarly constrained their range expansion since the Messinian. However, there is a possibility that both species compete strongly with each other if they come into contact or form hybrid populations. This remains highly speculative and requires further research. Further reading. Ferrito et al. 2013; Geiger et al. 2014; Buj et al. 2015; Cavraro et al. 2017 (phylogeography); Krijgsman et al. 2020 (Geology of the Aegean Sea).

Aphanius fasciatus ; Pag, Croatia; female, 35 mm SL. Aphanius fasciatus ; Qued Zahzah, Tunisia;male, 35 mm SL.