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Aphanius saourensis BLANCO, HRBEK & DOADRIO, 2006

Classification

Order: Cyprinodontiformes Family: Cyprinodontidae

Distribution

Endemic to the Oued Saoura river basin in Algeria, an endorheic (closed) drainage that does not run into the ocean but drains into the Sahara Desert and is often dry in its lower reaches. Previous collections of the species have occured in the Oued Zousfana tributary close to where it joins the Saoura at the town of Igli as well as the villages of El Ouata and Kerzaz further along the main Saoura channel but in 2004 it was only found at nearby Mazzer and is thought to have been extirpated from the other localities by an introduced Gambusia sp..

Although it has yet to be evaluated by the IUCN the authors of the 2006 description paper suggest it should be considered critically endangered. In 2004 what appeared to be the last remaining population was already outnumbered by Gambusia in a ratio of more than 100 to 1. Water was also being extracted for agriculture and runoff was causing pollution in some areas and it is conceivable that this species may now be extinct in nature.

Habitat

Images of the type locality depict a shallow, slow-moving stream with no marginal vegetation but dense growths of submerged plant-life.

Maximum Standard Length

A large female can measure 45 mm.

Aquarium SizeTop ↑

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 120 ∗ 30 cm.

Maintenance

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 therefore be filled with acrylic wool mops (use a fine grade if available) and ideally filamentous algae.

Fine-leaved plants such as Java moss or Ceratophyllum can also be used but may fail to thrive as the addition of marine salt to the water in a minimum ratio of 1-3 g/L is necessary. Similarly there is no need to add a substrate although inert sand or gravel can be added if you prefer and 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.

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: 7.5 – 9.0. It will probably not survive under acidic conditions.

Hardness: 179 – 536 ppm

Diet

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 aggressive spawning behaviour make A. saourensis a poor choice for the community aquarium. Given its clearly precarious conservation status the emphasis should 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. Males exhibit a mottled silver/blue patterning on the body which in some individuals forms rough bars towards the caudal peduncle. The dorsal, caudal and anal fin contain dark bars and tend to be faintly blue in colour while the paired fins are hyaline. Females are larger and much plainer possessing only some variable brown mottling on the flanks and completely hyaline finnage. Most have a single dark spot at the caudal peduncle.

Reproduction

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 November. 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 -14 days with the fry being large enough to accept Artemia nauplii, microworm etc. immediately after they become free-swimming.

NotesTop ↑

All Algerian Aphanius populations were considered to be representative of A. iberus until this species was described in 2006. It differs both morphologically and genetically from A. iberus and A. baeticus, probably diverging about 5.3 million years ago during the opening of the Straits of Gibraltar. It is most easily distinguished by the distinct mottled body patterning which in males of the other two species forms distinct vertical bars and in females dark spot-like markings.

A. iberus is now known to be restricted to Spain’s Mediterranean coastline so other Algerian populations from localities including the salt lakes of Chott Ech Chergui and Grande Sebkra d’Oran as well as the Oued Touil river basin may also have turned out to be distinct species. Unfortunately recent collection trips in these areas have failed and there is a lack of museum material meaning this may never be confirmed.

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 as there is at least one surviving captive population. 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.

The genus 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.

References

  1. Blanco, J.L., T. Hrbek and I. Doadrio 2006 - Zootaxa 1158: 39-53
    A new species of the genus Aphanius (Nardo, 1832) (Actinopterygii, Cyprinodontidae) from Algeria.
  2. 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).

One Response to “Aphanius saourensis”


  • It’s dead, Jim.

    ” In 2013, the German Killifish Association (DKG) in collaboration with Jörg Freyhof (IUCN FFSG chair the European Region) funded a small project to support Mahmoud Bacha and Chabane Benamirouche from Algeria to search again for the species at its type locality and other waterbodies in the Oued Saoura. Mahmoud and his team spent five days in the area and checked the type locality and all adjacent water bodies but with depressing results only. Beside Gambusia holbrooki, only alien tilapia (Oreochromis niloticus) could be found. This is the third extinct freshwater fish species in the Maghreb. There was no trace of the Aphanius. Naturally, a negative record is difficult to make and there might be still the chance to re-discover the species in the wild. But based on the actual results, we should treat the captive stock, which exist in some European countries, in a way as if the wild population would be gone.”

    http://joerg-freyhof.de/impressum/44-latest-news/424-aphanius-saourensis-extinct-in-the-wild


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