Aphaniidae, Hoedeman, 1949

Freyhof, JÖrg, Yoğurtçuoğlu, Baran, Jouladeh-Roudbar, Arash & Kaya, Cüneyt, 2025, Handbook of Freshwater Fishes of West Asia, De Gruyter : 697-698

Family Aphaniidae

Eurasian killifishes

The family comprises approximately 45 species, distinguished by the absence of ossified rays in the dorsal, a short and stout body, and sexually dimorphic colour patterns. The males typically exhibit prominent black or brown bars on the flank, while the females display a mottled or spotted colour pattern, with short black or brown lateral bars in some species. This resulted in numerous instances of dual descriptions of males and females as different species during the 19 th century when scientists were unaware of this sexual dimorphism. Extensive research was conducted on Aphaniids previously classified within the American family Cyprinodontidae . The definition, limits, and contents of the family Cyprinodontidae have undergone significant changes over the past 30 years. Aphaniidae is treated as its own family related to Valenciidae , which is endemic to Europe and African lamp-eyes ( Procatopodidae ). Aphaniidae has been subdivided into eight genera, with six of which (excluding Tellia and Apricaphanius ) are included in the coverage of this book. Aphaniids have a long fossil record, with the oldest Aphanius -like otoliths deriving from Miocene deposits almost 21 million years old. At which times, Aphaniids also occurred in Central Europe and the Caucasus region, and it is possible that they vanished from these regions due to climatic changes. The biology of most Aphaniids remains unknown in the field. However, they have been extensively studied in captivity. During the spawning period, which extends throughout spring and summer, year-round in some species, males establish territories along the shores, usually in dense vegetation but also between rocks, which they defend against rival males. Females spawn with one male, typically in algae or other vegetation close to the water surface or into gravel bottoms. If population densities are high, several males may sneak in to join the spawning pair. One or a few eggs are laid into the spawning substrate during a single spawning act. Individual females may spawn several egg clutches during a day and then typically pause for a few days before spawning again. Eggs possess filamentous structures to attach to the substrate. The larvae usually hatch after 7–15 days, with the timing dependent on temperature. Young Aphaniids exhibit rapid growth, with some reaching maturity within the same or the following year. Most species feed on algae, detritus, and small invertebrates. Several Aphaniids have very limited distribution ranges, with some species facing a high risk of extinction. One species is currently extinct. Ex situ populations of numerous species have been established within the aquarium hobby, yet they are poorly managed and typically based on a very small founder broodstock. Further reading. Parenti 1981 (phylogeny); Kottelat & Wheeler 2001 (nomenclature); Hrbek & Meyer 2003 (phylogeny, biogeography); ICZN 2003 (nomenclature); Freyhof et al. 2017b (family concept); Freyhof & Yoğurtçuoğlu 2020 (generic structure of Aphaniidae ); Kärst et al. 2020 (reproduction, ex situ maintenance).

Key to the genera of Aphaniidae in West Asia

The bars mentioned in the keys and the accompanying text are dark brown or black. The silvery white bars are referred to as interspaces. The key is largely based on the colour pattern of adult, nuptial individuals. It may be challenging to differentiate between immature individuals and those outside the spawning season.

1a - Head canals present, anterior supraorbital canal with 2–3 pores, posterior supraorbital canal with 2 pores, preopercular-mandibular canal with 6–7 pores.

………………2

1b - Head canals absent, cephalic sensory pores reduced to a series of neuromasts in small depressions, not connected to canals.

………………3

Open Access. © 2025 JÖrg Freyhof, Baran Yoğurtçuoğlu, Arash Jouladeh-Roudbar and Cüneyt Kaya, published by De Gruyter. the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

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2a - Caudal in male hyaline or white, often with yellow margin, with three wide, bold black bars, first bar situated on caudal base, shortly behind end of hypural complex, often faded (no bars in A. furcatus ); in nuptial female no dermal sheath around anterior anal rays.

……………… Aphaniops

2b - Caudal in male pale- or deep-yellow or orange, clearly distinct from silvery interspaces of flank bars; caudal with 0–2, often faint bars, no bar behind end of hypural complex; in nuptial female, dermal sheath, present around first few anal rays.

……………… Aphanius

3a - Teeth conical, in three rows; caudal peduncle very narrow, its depth 2.5–3.2 times in its length; body without scales. ……………… Kosswigichthys

3b - Teeth tricuspid, in one row; caudal peduncle deep, its depth 1.2–2.0 times in its length; body covered by scales, but reduced or absent in some species.

………………4

4a - Flank in male bluish, grey, or almost black with often irregular set and shaped, iridescent blue-white to silvery spots or bars often forming narrow vertical rows; male with very narrow, blue-white or silvery rows of spots or small blotches forming bands on black or blue caudal; female without diamond-shaped or roundish bold black blotch at mid-height of caudal base.

……………… Paraphanius

4b - Flank in male silvery with very regular set and shaped, rarely irregular, brown or black bars, overlaid with iridescent silvery spots in some species; male with bold, black or brown bars or with narrow brown bands on hyaline, white or yellow caudal, or caudal hyaline, with white margin in some species; female with diamond-shaped or roundish bold black blotch at mid-height of caudal base.

………………5

5a - Caudal in male without bars or rows of spots, with 1–5 indistinct vertical rows of small brown spots on proximal portion of caudal in some species; dorsal margin white, caudal and anal margins often white; if dorsal and anal margins black ( E. isfahanensis ) caudal without rows of spots or bars.

……………… Esmaeilius

5b - Caudal in male with 1–4 bold black bars or numerous vertical rows of small black or brown spots ( 4–14 in A. villwocki ); dorsal- and usually anal with margin black.

……………… Anatolichthys

An unidentified species of Anatolichthys was known from Syria in the early 20 th century (from Pellegrin 1923).