Taxonomy & naming
Jenkins described Esmaeilius pluristriatus in 1910 from material collected in the Mond River drainage of southern Iran, making it one of the earlier-named members of the genus. For much of the twentieth century its validity was disputed: some workers suggested it was a synonym of the more widespread A. sophiae, and the limited distributional data available did little to settle the question. The species was formally re-examined and reinstated by Esmaeili, Teimori, Gholami, Zarei and Reichenbacher in a 2012 Zootaxa monograph that compared meristic and morphometric data across the Iranian Aphanius assemblage.
The 2012 re-description demonstrated that E. pluristriatus differs from A. sophiae, A. farsicus, and A. isfahanensis in a combination of three diagnostic characters: a smaller caudal peduncle index, a higher number of vertical flank bars in males, and a lower gill-raker count. Phylogeographic reasoning in the same paper suggested the population is a Quaternary relict derived from an ancient A. sophiae stock that colonised what is now the Bushehr Basin via the Paleo-Kor River system during a period of connected drainage. Eschmeyer's Catalog of Fishes (Fricke, Eschmeyer & van der Laan) records the current valid combination as Esmaeilius pluristriatus (Jenkins, 1910), within the family Aphaniidae (formerly treated as Cyprinodontidae in part).
The genus Aphanius as a whole represents the eastern arm of the Old World toothcarp radiation, distributed from the Iberian Peninsula and North Africa across the Middle East to Pakistan. Within that genus, E. pluristriatus occupies the Iranian Gulf-drainage cluster alongside A. sophiae, A. farsicus, and A. isfahanensis.
This fish was long listed as Aphanius pluristriatus; Eschmeyer's Catalog of Fishes places the species in Esmaeilius, and the current combination Esmaeilius pluristriatus (Jenkins, 1910) is followed here. It is a distinct species, not a synonym of Esmaeilius sophiae.
Morphology
Esmaeilius pluristriatus is a compact, sexually dichromatic toothcarp. Specific standard-length data are sparse in the primary literature for this species, but it falls within the typical Aphanius size range of roughly 1.2–2 in SL, with males smaller and more vividly coloured than females.
Males display a dark brown to blackish head and body overlaid with 14–16 narrow vertical white bars running along the sides from the ventral margin up to approximately the level of the dorsal fin origin. The operculum carries small, irregularly arranged brownish spots, and the fins are yellowish-brown with white margins on the median fins; the lower edge of the pectoral fin is tinged black. This bar count — at the high end of what is seen in Iranian Aphanius — is one of the key diagnostic characters separating the species from its congeners.
Females are more cryptically patterned: the flank bars of the male are absent, replaced by dark, wavy, irregularly arranged vertical pigment patches on a paler background. A distinctive oval to lozenge-shaped dark spot marks the base of the caudal fin in females, a character also useful for field identification. The opercular spot pattern is present in both sexes.
Habitat
The entire known range of Esmaeilius pluristriatus lies within two sites in the Bushehr Basin of southwestern Iran: the Zarjan spring system east of Shiraz near Fasa, which constitutes the type locality and drains into the Mond River, and a qanat (traditional subsurface irrigation channel) system near the town of Jahrom, also within the Mond River catchment. Both sites are permanent freshwater habitats — spring-fed pools and the shallow, stone-lined channels of the qanat — set in an otherwise arid landscape.
The Zarjan springs support a modest fish community alongside E. pluristriatus: Keivany and Esmaeili (2014) recorded co-occurrence with the bleak Alburnus mossulensis, the spirlin-like Capoeta damascina, the doctorfish Garra rufa, and two introduced poeciliids — the mosquitofish Gambusia holbrooki and the swordtail Xiphophorus hellerii. The presence of introduced poeciliids is ecologically significant and directly threatening. Water chemistry data specific to this locality are not available in the published sources, but the Mond Basin geology (predominantly calcareous formations) and the arid regional climate point toward hard, well-oxygenated, neutral-to-alkaline spring water typical of the Iranian plateau's gulf-draining catchments.
The fish's restriction to spring and qanat systems — rather than the main river channel — reflects a pattern common to many Aphanius species: they occupy the stable, year-round flow of groundwater-fed habitats that persist through the dry season when the broader river system may reduce dramatically.
Feeding
No dedicated dietary study of Esmaeilius pluristriatus has been published, and stomach-content data from the primary sources are absent. Inference from the broader genus and from its co-occurrence guild provides reasonable guidance. Aphanius species are generally opportunistic omnivores, consuming algae, detritus, small invertebrates (insect larvae, copepods, ostracods), and organic plant matter in proportion to their availability — a trophic position typical of small toothcarps occupying shallow, productive spring habitats.
In aquaria, Aphanius toothcarps are straightforward to feed and accept a wide range of foods: high-quality flake or micropellet staples, frozen or live Artemia nauplii and Daphnia, small bloodworm, and any other appropriately sized invertebrate-based food. Because the species inhabits hard, alkaline water in nature, the mineral content and pH of the water in captivity matter more to long-term health than fine-tuning the diet.
Mating
Esmaeilius pluristriatus is a non-annual killifish. Its type locality and additional known site are permanent spring and qanat habitats — there is no seasonal desiccation that would favour the evolution of diapausing annual eggs. The species reproduces as a plant or substrate spawner, placing adhesive eggs on fine-leaved vegetation, algal mats, or similar surfaces over an extended season rather than burying eggs in substrate for a dry-season rest.
Keivany and Esmaeili (2014) established that spawning in the wild occurs between April and July, consistent with the warm-spring to early-summer period when water temperatures are rising and productivity in the springs is highest. Sex-ratio data from a 2003 collection of 151 individuals returned a female-biased ratio of approximately 1.1F:1M, which may reflect differential microhabitat use by the sexes or the normal demographic pattern for this species.
As in other Aphanius, males are presumed to establish loose territories or display actively toward females in the shallows during the breeding season. The vivid vertical barring of males likely functions as both species-recognition and mate-quality signal in the clear, sunlit spring water.
Breeding
Total fecundity data from wild-caught Esmaeilius pluristriatus are available from Keivany and Esmaeili (2014): absolute fecundity ranged from 35 to 255 eggs per female, with a mean of approximately 162 eggs. This is a relatively low clutch size, consistent with a non-annual species that spreads reproduction across a multi-month season rather than concentrating a single large batch before a habitat dries. Eggs are adhesive and are deposited singly or in small clusters on plant surfaces or among submerged vegetation, where they incubate in water with no diapause phase.
In captivity, Aphanius toothcarps breed readily when maintained in appropriate hard, alkaline water with males and females present. Conditioning on live and frozen invertebrates and a gradual temperature rise in spring are effective cues. A fine-leaved plant such as Java moss, or a synthetic spawning mop, provides the necessary egg substrate. Because adults may consume eggs, the spawning mop can be transferred to a separate rearing vessel for hatching. At warm temperatures (75–79 °F) eggs hatch in approximately 8–12 days; fry are small but robust and accept Artemia nauplii from first feeding. Given the species' rarity and conservation status, any captive breeding effort has genuine conservation value.
In the aquarium
Esmaeilius pluristriatus is virtually unknown in the hobby outside specialist circles focused on Iranian and Middle Eastern toothcarps. It has not entered the general aquarium trade, and captive stocks — where they exist — are held almost entirely by killifish societies with a specific interest in Aphanius and related genera. Obtaining the species requires contact with those networks rather than normal retail channels.
Care requirements follow the Aphanius template: a small to medium aquarium (23.6–31.5 in) is sufficient for a breeding group, furnished with live or artificial fine-leaved plants and an open swimming area. The critical parameter is water chemistry — hard, alkaline conditions (general hardness >10°dGH, pH 7.2–8.5, temperature 64–79 °F) are necessary; the soft, acidic water typical of South American killifish is unsuitable. A species tank or one shared with other hard-water dwellers is preferable; the fish should not be kept with aggressive species or very fast-moving fish that would outcompete them at feeding.
Given the perilous state of wild populations, Esmaeilius pluristriatus deserves greater attention from the specialist aquarium community. Maintenance of genetically diverse captive stocks in killifish societies represents a meaningful conservation contribution, particularly since in-situ protection of the Zarjan spring system has not been formalised.
Conservation
Esmaeilius pluristriatus has not been formally assessed by the IUCN Red List — an omission that Keivany and Esmaeili explicitly flagged in 2014, noting that the species meets the criteria for a threatened listing under multiple Red List categories given its extremely restricted range, ongoing habitat degradation, and invasive species pressure. All known populations are confined to a single river drainage (Mond) and encompass at most two sites: the Zarjan spring complex and a qanat near Jahrom. Such geographic confinement, combined with the pattern of threats documented below, would almost certainly qualify the species for Critically Endangered or Endangered status upon formal assessment.
The Zarjan type-locality springs have been severely degraded: recurrent drought — intensifying under recent regional climate trends — has reduced spring flow, while infrastructure conversion has turned portions of the spring system into concrete-lined canals that eliminate the natural bank vegetation and substrate heterogeneity the fish requires for spawning. Pollution from agricultural run-off and domestic waste adds a further stressor. The introduction of Gambusia holbrooki (mosquitofish) and Xiphophorus hellerii (swordtail) to the type locality creates competition and potential predation pressure on eggs and fry — a combination documented as catastrophic for numerous Aphanius and other toothcarp populations across the Middle East and Mediterranean.
No formalised legal protection for the Zarjan springs or conservation management plan for E. pluristriatus was reported in the available sources as of 2014. Effective protection would require spring-flow preservation, removal or containment of introduced poeciliids, and formal IUCN assessment to raise the species' conservation profile. Ex-situ culture by killifish societies provides insurance against total extinction but is not a substitute for securing the wild habitat.