Esmaeilius arakensis
Arak Toothcarp
SynonymsTop ↑
Aphanius arakensis Teimori, Esmaeili, Gholami, Zarei & Reichenbacher, 2012
Etymology
Esmaeilius: named for Iranian ichthyologist Hamid Reza Esmaeili “for his extensive contribution to the understanding of diversity within this genus”, in combination with the Latin suffix -ius, indicating ‘belonging to’.
arakensis: named for the city of Arak in Markazi Province, northwestern Iran, which is located close to this species’ type locality, in combination with the Latin suffix -ensis, meaning ‘of or from’.
Classification
Order: Cyprinodontiformes Family: Aphaniidae
Distribution
Appears to be endemic to a small part of the Namak Lake basin in Qom province, northern Iran, where it’s restricted to a handful of natural springs near the city of Arak.
Habitat
Namak is an endorheic salt lakelying south of the Alburz (Elburz) Mountains, east of the Zagros Mountains, west of the Kavir basin, and north of the Kuh-e Karkas range. It covers an area of approximately 1800 km² of which the majority is permanently dry, while temperatures can range from -6°C/21.2°F-35°C/95°F with a mean annual average of 13.5 ºC/56.3°F.
The habitats of A. arakensis are not contained within the lake itself but are included in the Namak basin as they’re not separated by any major landform. The type locality is a small, shallow pond formed by a nearby natural spring and measures approximately 6 m x 4m.
The substrate is composed of mud and gravel with no aquatic plants although there are some Juncus sp. and Typha sp. growing around the margins. When field studies were conducted the water was almost stagnant with a temperature of 23°C/73.4°F and the habitat is described as being in a ‘bad condition due to anthropogenic pollution’.
A. arakensis was the only fish species inhabiting the pool but others endemic to the Namak basin include Barbus miliaris, Capoeta buhsei, and Paracobitis iranica.
Maximum Standard Length
30 – 35 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 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: 8 – 32 °C
pH: 7.0 – 8.5
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 vegetable content to the diet.
Behaviour and CompatibilityTop ↑
Its particular water requirements and aggressive spawning behaviour make A. arakensis a poor choice for the community aquarium. Given its 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 series of silvery vertical bars in the rear portion of the body with sometimes 2-3 lighter bars in the caudal fin. The dorsal, anal, and caudal fins have white margins, the anterior dorsal-fin rays are dark, and the pectoral and pelvic fins yellowish. Most specimens possess dark blotches at the base of the dorsal and anal fins.
Females are larger, plainer, and possess a series of dark markings on the flanks, while all fins are whitish.
Reproduction
A. arakensis exhibits a reproductive strategy adaptated to unstable environments and fluctuating population sizes with a relatively short lifespan (<3 years in most cases), early sexual maturity and a high reproductive effort. 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 with peaks in April and August.
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 ↑
This species was available in the aquarium hobby for a number of years prior to publication of the official description and was generally referred to as A. sp. ‘Namak’ or A. sp. ‘Namak River’.
It can be distinguished from other members of the genus by the following combination of characters: 10–12 anal-fin rays; 28–32 lateral line scales, 10–13 caudal peduncle scales; 8–10 gill rakers; 12–19, commonly 15-16, clearly-defined flank bars in males; prominent pigmentation along the flanks comprising relatively large blotches in females; a short but high antirostrum of the otolith with a wide excisura, and a ventral rim with some small, drop-like processes; 19 molecular apomorphies (17 transitions, two transversions) in the cytochrome b gene.
Among congeners it’s most closely-related to A. farsicus and A. sophiae and externally it appears very similar to both. Such morphological similarity is not uncommon between Aphanius spp. inhabiting similar environments though they may be quite far-removed from one another in a genetic sense, with shared environmental variables thought to act as a stabilising factor in terms of morphology.
This may explain why speciation events have tended to primarily affect genetic factors rather than morphology in Aphanius spp., and why rapid genetic diversification has repeatedly occurred in the absence of comparable morphological changes.
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.
References
- Teimori, A., H. R. Esmaeili, Z. Gholami, N. Zarei, and B. Reichenbacher, 2012 - Zookeys 215: 55-76
Aphanius arakensis, a new species of tooth-carp (Actinopterygii, Cyprinodontidae) from the endorheic Namak Lake basin in Iran.
