Taxonomy & naming
Paraphanius similis was originally described by the Turkish ichthyologist F. Akşiray in 1948 as a subspecies, Aphanius sophiae similis — grouped, like its close relative P. mentoides, with the Iranian Zagros toothcarp Aphanius sophiae (now Esmaeilius sophiae) under the broader species concept applied to Middle Eastern Aphaniidae at the time. Eschmeyer's Catalog of Fishes now recognises similis as a full species, and, following the genus-level revision that placed the Levantine and Anatolian mento-group toothcarps in the resurrected genus Paraphanius, the currently valid combination is Paraphanius similis (Akşiray, 1948).
The epithet similis — Latin for 'similar' or 'like' — is characteristically noncommittal, the kind of provisional epithet a describer applies when a population's precise affinities are not yet resolved; it stands in useful contrast to its sister taxon's epithet mentoides ('mento-like'), which more explicitly anticipated the eventual placement of both forms within the mento group. Together, mentoides and similis illustrate how the original, broad Aphanius sophiae concept of the 1940s has since been unpacked into geographically and phylogenetically distinct lineages spanning Iran (Esmaeilius sophiae) and Anatolia/the Levant (the Paraphanius mento group).
This fish was long listed as a subspecies of Aphanius sophiae (as Aphanius sophiae similis); Eschmeyer's Catalog of Fishes recognises it as a full species in the genus Paraphanius, and the current combination Paraphanius similis is followed here.
Morphology
Dedicated morphological description of Paraphanius similis beyond the original 1948 subspecies account is sparse in the sources consulted. By analogy with its close relatives P. mento and P. mentoides, a broadly similar size — roughly 2–3 in — and body form is expected: compact, moderately deep-bodied, with the upturned, underslung jaw characteristic of the mento group.
Sexual dichromatism can be expected to follow the pronounced pattern typical of Paraphanius: males darkening toward near-black or steel-grey in breeding condition with rows of iridescent blue-silver spots or bars, and females considerably plainer, pale tan to cream with fainter markings and largely transparent fins. Species-specific colour-pattern description and measurements for similis were not located and should be treated as provisional pending a modern redescription.
Habitat
Specific, published locality data for Paraphanius similis were not located in the sources consulted. Given its original description as a geographic form within the broader sophiae/mento complex, and its current placement with the mento group of Paraphanius, the species most plausibly occupies hard-water springs, streams, or wetland margins somewhere in the eastern Anatolian, northern Levantine, or Tigris–Euphrates headwater zone — the general contact area between the ranges of Paraphanius mento and Esmaeilius sophiae.
As with all documented Paraphanius, hard, alkaline water is expected, likely with the same intolerance of soft or acidic conditions that characterises P. mento. This habitat account should be read as inferred from the species' taxonomic and geographic context rather than direct field survey data, which was not located for this specific population.
Feeding
No dedicated dietary study of Paraphanius similis was located. By analogy with Paraphanius mento, an omnivorous diet with a vegetarian tendency is expected — algae and plant material alongside small invertebrates and insect larvae in the wild. In captivity, congeners of this genus accept live and frozen Artemia, Daphnia, and bloodworm readily, with dried and flake foods generally accepted less enthusiastically than fresh items.
Mating
Species-specific breeding behaviour for Paraphanius similis has not been documented in the sources consulted. As a presumed inhabitant of permanent hard-water habitat, it is expected to follow the non-annual, continuous or fractional spawning mode documented in detail for its close relative P. mento — small batches of adhesive eggs deposited on vegetation or algae across an extended warm-season period, with no diapause phase. Males of the mento group are notably territorial and can be aggressive toward rivals and toward females during courtship, a trait that may extend to this species as well.
Breeding
No published breeding or aquarium-propagation account for Paraphanius similis was located. By analogy with P. mento, eggs would be expected to be adhesive, hatching in roughly one to two weeks at typical temperatures without diapause, with fry able to take newly hatched Artemia nauplii from an early stage. This account should be treated as inferential rather than field- or captive-verified, given the species' apparent absence from the published breeding literature and the aquarium hobby.
In the aquarium
Paraphanius similis does not appear to be an established aquarium species; no hobbyist husbandry accounts were located in the sources consulted, and it is likely unfamiliar even to most specialist killifish keepers who maintain its better-known relative P. mento. Prospective keepers should not expect to source this species through ordinary aquarium trade channels.
Where the species might be maintained, care would be expected to follow the well-documented P. mento template: hard, alkaline water (the fish will not tolerate soft, acidic conditions), a secure lid against jumping, and separation of aggressive males where multiple are kept together. Given the species' Critically Endangered CARES classification, any confirmed captive holdings would carry particular conservation value and should be managed through documented, coordinated breeding programmes rather than casual trade.
Conservation
Paraphanius similis carries a CARES Fish Preservation Program priority listing, recorded under its historical subspecies-style designation Aphanius mento 'similis' and classified Critically Endangered (CCR) — the most severe conservation classification among the Akşiray 1948 Anatolian toothcarp taxa newly documented in this atlas, and a strong signal that whatever population underlies this name is under acute, likely near-term threat.
No species-specific IUCN Red List assessment was located. The broader conservation picture for the eastern Mediterranean and Middle Eastern hard-water toothcarp fauna is one of severe, well-documented pressure: coastal lagoons and spring systems across the region are drained or modified for agriculture and development, groundwater is over-pumped for irrigation, and the introduced mosquitofish Gambusia holbrooki has spread widely as an intended mosquito-control measure, with well-documented predatory and competitive impacts on native Aphaniidae — the same combination of threats responsible for the near-total collapse of several better-studied Anatolian Aphaniidae, including the single-spring survivor Anatolichthys transgrediens. Given the Critically Endangered CARES classification and the near-total absence of published locality or population data, a targeted field survey to locate and characterise the surviving population(s) of P. similis would be the essential first step toward any meaningful conservation response.