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Aphanius villwocki HRBEK & WILDEKAMP, 2003


Order: Cyprinodontiformes Family: Cyprinodontidae


Endemic to the Sakarya River basin including Lake Çavuşçu (Çavuşçu Göl) in western central Turkey. The river originates to the south of Eskişehir city and initially flows to the east and slightly south before turning northwards where it meets the Porsuk River before winding through the Sündiken mountains and emptying into the Black Sea.

A. villwocki has only been found below the confluence with the Porsuk and is probably restricted to the upper section of the system where it is reproductively isolated from other members of the genus found in central Turkey. See the ‘notes’ section for a little more on the distribution of Aphanius in the region.

The fish exhibit some variations in colouration and patterning depending on locality. It is therefore important that the different forms be labelled with the collection details by hobbyists and scientists alike in order to preserve bloodlines and maintain accuracy e.g. “Pınarbaşı”, “Ahiler”, “Abbashalimpaşa”, etc.


This species is highly adaptable and occupies a number of habitat-types. For example the type locality (at Pınarbaşı, east of Emirdağ) is the drainage canal of a spring-fed pond containing clear freshwater with aquatic vegetation consisting of Potamotegon and Nasturtium spp. Typha sp. bullrushes grow around the margins and the substrate is composed of sand and gravel. Unfortunately the introduced, highly competitive Gambusia affinis has also been recorded here; Gambusia species are having a deleterious effect on Aphanius populations throughout their natural range.

On the other hand Lake Çavuşçu is hypersaline and is only occasionally inundated with fresh water via temporary streams that form during periods of high rainfall, connecting it to the Sakarya across the Yigar plain. A. villwocki inhabits the lake itself as well as surrounding marshes. At the northern end of the Yigar plain yet another population was discovered in a thermal stream at the village of Imamoğlu.

Maximum Standard Length

50 – 60 mm.

Aquarium SizeTop ↑

A pair or trio can be kept in a container with base dimensions of 60 cm x 30 cm or so but as a general rule members of this genus do best when maintained as a larger group in a space measuring upwards of [dimensions].


Even for long-term maintenance a simple set-up will suffice. The most important factors are the provision of many broken lines of sight and a suitable medium in which the fish can deposit eggs. Female and subdominant male individuals must be offered the opportunity of respite from the aggressive alpha males during the spawning season so much of the available space can be filled with acrylic wool mops (use a fine grade if available), clumps of java moss or Ceratophyllum and ideally filamentous algae. There is no need to add a substrate although inert sand or gravel can be added if you preferand filtration need not be too strong either.

It is possible, and preferable, to maintain it outdoors all year round in many countries and it will show better colours and overall condition if exposed to at least a few hours of natural sunlight each day. Try to find out the origin of your fish as some populations will do best with the addition of marine salt in the ratio of 1-3 g/L.

Water Conditions

Temperature: Active over a wide temperature range of 2 – 30 °C. Artificial heating is not required in all but the coldest climates and it should be provided with a ‘winter’ period of several months during which it is maintained at low temperatures or it is likely to suffer both reduced fecundity and a shortened lifespan.

pH: The pH value in its natural waters ranges between 6.5 – 8.5 and we suggest aiming for similar values in aquaria. It will probably not survive under more acidic conditions.

Hardness: 179 – 536 ppm


Aphanius species are basically micropredators feeding on small aquatic crustaceans, worms, insect larvae and other zooplankton although algae and other plant material is also taken at times. In the aquarium they will learn to accept dried foods in most cases but should also be offered regular meals of small live or frozen fare such as Artemia, Daphnia or bloodworm. This is particularly important during the months of spring and summer due to their high reproductive effort throughout this period. If the aquarium or container does not contain filamentous algae try to introduce a good quality dried product with added Spirulina content to the diet.

Behaviour and CompatibilityTop ↑

Its particular water requirements and vigorous spawning behaviour make A. villwocki a poor choice for the community aquarium. Given its rarity in the hobby the emphasis should also be on captive reproduction and we strongly recommend maintaining it alone. It should be kept in a group with a ratio of two or three females to each male being the ideal.

Sexual Dimorphism

As with all members of the genus sexual dimorphism is pronounced. The body of the male is yellowish and possesses a series of 13-19 whitish vertical bars on the flanks with usually one or more lighter bars composed of yellow spot-like markings in the caudal fin. The dorsal and anal fins contain yellow flecking throughout and a thick, dark marginal band. Females are larger and much plainer possessing only a dark spot on the caudal peduncle, sometimes some smaller spots in the rear half of the body and completely hyaline finnage.


Captive reproduction is not difficult if the tank or container is properly arranged and maintained (see ‘tank set-up’). It is a fractional spawner with females depositing eggs on a more-or-less continuous basis between the months of April and September. Males form temporary territories which they defend against rivals while attempting to entice females to spawn. Dominant individuals will show more intense colouration. Eggs are released singly or in small batches and are attached to algae or other surfaces by means of small filaments. Aphanius typically eat their eggs/fry and the medium should therefore be checked on a daily basis during the spawning period.

The eggs are very small and must be treated carefully. Use a fine pair of forceps to gently remove pieces of medium with eggs attached whilst avoiding contact with the eggs themselves. Alternatively the entire medium can be removed and replaced every couple of days. The medium/eggs should be transferred to a container with water of the same chemistry and temperature as that of the adults. The incubation period can vary a little with the temperature but is usually between 7 – 15 days with the fry being large enough to accept Artemia nauplii, microworm etc. immediately after they become free-swimming.

NotesTop ↑

Prior to its description this species had been considered a form of A. anatoliae and also referred to as A. sp. aff. danfordii but collections in the early part of this century motivated new studies and resulted in its elevation to full species level. Phylogenetic analyses have shown it to represent the sister group to all other Anatolian Aphanius.

The Anatolia region represents a centre of diversity for the genus with ten endemic species described to date. These are thought to have diverged as a result of the splitting of what was originally a vast lake covering much of modern Anatolia. Two separate divergence events occured, the first resulting in the western separation of A. asquamatus, A. danfordii and A. villwocki around 12-15 million years ago (possibly earlier in the case of A. asquamatus). 

Lakes Tuz, Eğirdir and Beyşehir are remnants of the central part of the lake where A. a. anatoliae now occurs and there also exist three subspecies in the Turkish Lakes region that were isolated when the eastern end of the lake became disconnected around 11-12 mya. They were further separated from one another 7-8 mya and have evolved independantly to survive in bitter lake environments containing high levels of alkaline carbonates and sulfates. Due to an historic lack of competition, predators and aquatic vegetation in their habitats they have developed distinctive limnetic (open water) characteristics including an elongated, relatively slim body shape and unique jaw morphology.

You’re unlikely to find it on sale in aquatic stores although it may be available via specialist breeders or associations from time-to-time. While Aphanius are certainly not as colourful as some of their relatives their interesting behaviour and continuous activity make them fascinating aquarium subjects and well worth a try if you possess the dedication to take on a long-term maintenance project since conservation is key with all members of the genus.

It currently contains 22 species and subspecies which are thought to have derived from a common ancestor originally distributed around the periphery of the former Tethys Sea. None are particularly well-documented in aquarium literature although some are very beautiful and the majority are not too difficult to maintain and breed. Sadly most are on the verge of extinction for one reason or another with several existing only in remnant, highly-localised populations. 

In practically all cases the root cause for this decline is the activity of humans and although some species are now protected by conservation law the mismanagement and degradation of their habitats continues at an alarming rate. A few species are still sometimes listed as members of Lebias although that name has long been considered a synonym of Cyprinodon by most authorities and an ICZN committee voted to suppress the name in favour of Aphanius as recently as 2003.


  1. Hrbek, T. and R.H. Wildekamp, 2003 - Ichthyological Exploration of Freshwaters 14(2): 137-144
    Aphanius villwocki, a new species from the Sakarya River basin of central Anatolian plain, Turkey (Teleostei: Cyprinodontiformes).
  2. Bardakci, F., N. Tatar and T. Hrbek, 2004 - Biologia, Bratislava 59(5): 559-566
    Genetic relationships between Anatolian species and subspecies of Aphanius Nardo, 1827 (Pisces, Cyprinodontiformes) based on RAPD markers
  3. Hrbek, T. and A. Meyer, 2003 - Journal of Evolutionary Biology 16(1): 17-36
    Closing of the Tethys Sea and the phylogeny of Eurasian killifishes (Cyprinodontiformes: Cyprinodontidae).
  4. Hrbek, T., F. Küçük, T. Frickey,K. N. Stölting, R. H. Wildekamp and A. Meyer, 2002 - Molecular Phylogenetics and Evolution 25(1): 125-137
    Molecular phylogeny and historical biogeography of the Aphanius (Pisces, Cyprinodontiformes) species complex of central Anatolia, Turkey.
  5. Wildekamp, R.H., F. Küçük, M. Ünlüsayin, and W. V. Neer, 1999 - Turkish Jounal of Zoology 23: 23-44
    Species and Subspecies of the Genus Aphanius Nardo 1897 (Pisces: Cyprinodontidae) in Turkey.

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