Type locality, Peloponnese: Korinthia Distr. Brackish water spring Kokosi at southern end of Almiri beach, at Kato Almiri, about 4 km south of Loutra Elenis, MHNG 2654.087 (holotype of Aphanius almiriensis, 35.1 mm SL).

There are only two populations known to date, in the spring near Almiri (Saronikos Gulf) and in the Meligou lagoon (Argolikos Gulf). Almiri spring is a permanent brackish water spring (23 ppt) adjacent to the sea, which it joins after a few meters; the spring itself is now contained by a concrete wall and the enclosure is filled with typical halophytic aquatic vegetation. Meligou lagoon is a permanent brackish marsh (11-25 ppt). Until the second half of the 20th century it occupied an area of about 2.6 square km, later on, reclamation works reduced its surface area to 1.5 square km. There is a spring along the west side of the lagoon, with permanent freshwater discharge. The species is observed in shallow areas with slow current, among vegetation, as well as in the water column. It is a very fast swimmer and forms schools. It is a short-lived species and a fractional spawner that breeds in late spring to early summer, spawning 1-3 eggs a time. However, since larvae were collected in Meligou in September 1998, its reproductive period may be prolonged until late summer. This species was discovered in 1997 in the Almiri spring, which at the time released brackish water of constant salinity. Between 1997 and 2000, the observed salinity was 23 ppt. however, by 2002 the spring was releasing pure seawater, the only fish observed were mugilids and was occupied by unidentified sea grasses and sea anemones, that the species was then believed to be extinct. A visit in October 2003, however, yielded 5 juveniles (13.4-22.1 mm SL), but by July 2004, despite intensive search, no A. almiriensis were observed in Almiri. After realizing the distinctness of the Almiri population, older collections were re-examined for possible additional localities; a sample obtained in Meligou lagoon in October 1998 was discovered. In this sampling occasion, the species was estimated as abundant in the main freshwater spring supplying the lagoon at its NW side. However, recently, this spring was dammed with rocks, to create a 'natural swimming pool'. During a visit in July 2004, no fish were present in the modified spring area, but this species was collected from different areas of the lagoon (Ref. 58344).

Status of threat: critically endangered (Ref. 58344).