Cichlids are found in fresh and brackish waters of Central and South America, Africa, Madagascar, the Levant, southern India, Sri Lanka and southern Iran. There are over 1300 species (with several hundred more to be described) (Nelson, 2006) but only 1 is found in Iran. Maximum length is about 80 cm.

Cichlids are distinguished by having only a single nostril on each side; practically all other fishes have two nostrils. The lateral line is in 2 parts, an anterior and higher portion ending under the soft dorsal fin and a lower, mid-flank, posterior part beginning below where the first part ends and continuing to the tail base, usually 7-25 spines in the dorsal fin followed by 5-30 soft rays, anal fin usually with 3 spines, but some species have 4-9 or 12-15 spines, followed by usually 4-15 soft rays, scales ctenoid or cycloid, extending onto the head, a specialised pharyngeal bone in the throat breaks up food by pressing it against a hard pad on the skull base, mouth dentition highly specialised in relation to diet with scraping (for algae on rocks), pointed (to seize fish), crushing (for hard-shelled molluscs), winkling (for removing snails from their shell or picking eyes) or reduced and embedded (for egg eating). Body form varies greatly between species and many are colourful and highly prized as aquarium fishes. They are often highly territorial, defending a breeding area against all invaders. They are most common in still waters where there are branches, rocks or plants. Some cichlids are important food fishes but they have attracted scientific attention for their elaborate breeding behaviour and evolutionary history. Certain cichlids, for example, are mouthbrooders, carrying eggs and fry in their mouths to protect them, while others spawn on the substrate, build nests or nourish young from a skin secretion. African lakes contain rich species flocks of cichlids which show various feeding behaviours. How these species arose and adapted to different ways of life have been important to scientists in understanding the mechanisms of evolution and adaptation.

Murray (2001) reviews the fossil record and the biogeography of the family and suggests an origin less than 65 MYA in the Early Tertiary in contrast to other studies that give an origin over 130 million years ago. Their salinity tolerance has enabled them to cross marine barriers.

Genus Iranocichla
Coad, 1982

The genus is monotypic so its description is subsumed under the species account.

Iranocichla hormuzensis
Coad, 1982

Colour photographs of males (females in background) courtesy of Thomas Schulz

Common names

siklid Irani, siklid-e Hormuz, cichlid-e Hormoz.

[Hormuz cichlid, Iranian cichlid]

Systematics

Trewavas (1983) relates this species to Danakilia Thys van den Audenaerde, 1968, a monotypic species from northeast Africa, on the basis of the low gill raker count, lower pharyngeal bone and teeth morphology, and morphometric characters such as a deep preorbital depth, long snout, head length and the small eye. Trewavas (1983) places Iranocichla in Danakilia but also agrees with Coad (1982a) that Iranocichla (and Danakilia) may be related to species in the genus Tristramella Trewavas, 1942 of the Jordan River basin and that this requires further investigation. I retain Iranocichla as a distinct genus until these relationships are examined more closely as some of the characters used to relate Danakilia and Iranocichla may be common responses to temperature and salinity extremes. In addition, Trewavas (1983) suggests a possible relationship of Danakilia with Oreochromis alcalicus (Hilgendorf, 1905) of the African Rift Valley. This species too is found in waters of high temperature and mineral content. Klett and Meyer (2002) group this genus with Sarotherodon, Oreochromis and Tristramella on mitochondrial NADH dehydrogenase subunit 2 gene sequences.

The type locality is the "Mehran River at 27°04'N, 54°35'E, Hormozdgan Province" (Coad, 1982a). The holotype, 94.2 mm standard length, is a female with eggs in the mouth held in the Canadian Museum of Nature, Ottawa under CMNFI 1979-0408A (see figure above). Paratypes are CMNFI 1979-0408B, 15, 24.3-86.5 mm standard length, same locality as the holotype and CMNFI 1979-0139, 35, 29.6-95.2 mm standard length, stream in Rasul River drainage between Chahar Berkeh and Tang-e Dalan, ca. 27°25.5'N, 54°59'E, Fars-Hormozgan border. Paratypes were deposited in the British Museum (Natural History), London under BM(NH) 1981.1.12:1-2 (2 specimens), Muséum national d'Histoire naturelle, Paris under MNHN 1981-107, 108 (2), California Academy of Sciences, San Francisco under CAS 47324 (2), the Royal Ontario Museum, Toronto under ROM 36389 (1) and the University of British Columbia, Vancouver under BC 81-1 (1).

Key characters

This is the only cichlid species in Iran, easily recognised by the single nostril opening on each side of the head.

Morphology

This cichlid is uniquely characterised by a nearly circular dental field on the lower pharyngeal bone, the teeth there being of uniform size and not enlarged medially and by cheek, operculum, belly, isthmus and area between the pectoral and pelvic fin bases naked or poorly scaled. Other significant characters are the posteriorly rounded dorsal and anal fins, short pectoral fins not reaching the vent, cycloid scales with granular posterior circuli bearing rounded or irregular protuberances, inferior apophyses for support of the swimbladder centred around the fourth vertebra (figured in Coad (1982a)), mesethmoid not meeting the vomer, modal vertebral count 29, median length of lower pharyngeal bone 31.8-40.9% (mean 35%) length of head, and pharyngeal blade/median length toothed area 0.6-1.0, mean 0.8.

Scales are regularly arranged on the flanks except that in some large specimens the regular scale rows are interspersed with irregularly distributed smaller scales, particularly on the upper flank. Scales may be absent entirely from the head, sparse above the lateral line anteriorly and on the belly posterior to the pelvic fins, absent from the dorsal and anal fin bases, absent from between the pectoral and pelvic fin bases and on the belly and isthmus anterior to the pelvic fins. However, in other specimens the head may be scaled dorsally to above the eyes, with scales variably imbricate, there may be 2-3 rows containing 4-7 minimally or non-imbricate scales on the cheek which is never completely scaled. The dorsal border of the opercle may have two large scales next to each other and a single scale may be present over the centre of the subopercular bone. Scales may be present on the whole belly, isthmus and between the pectoral and pelvic fin bases, but they are minute, embedded, and non-imbricate. Their extent and number varies between individuals. Small to minute scales, numbering up to about 20, are present on the caudal fin base, extending distally onto the fin membranes for more than half the fin ray length in some specimens.

Flank scales below the mid-point of the spiny dorsal fin and beneath the upper lateral line are cycloid or very weakly ctenoid. The focus is central and there are 9-14, mean 12.4, radii on the anterior field based on 5 scales from 7 adult specimens 59.2-87.1 mm standard length. Posterior circuli are granular so the exposed scale surface has rows of rounded or irregular protuberances.

The gut is a tightly coiled spiral with its apex ventral. Gut length in 5 specimens (59.2-90.5 mm standard length) is 6.8-8.3, mean 7.6, times the standard length. Gill rakers are short and rounded, reaching the adjacent raker or a little further when appressed.

The pharyngeal apophysis is of the Tilapia type (Greenwood, 1978). The mesethmoid does not meet the vomer, the intervening space being cartilaginous. Pores at the openings of the cephalic lateral line canals on the preorbital and preoperculum are single not multiple. The inferior apophyses for support of the anterior end of the swimbladder involve vertebrae 2 to 5, the fourth vertebra being involved in 8 out of 10 fish examined.

Teeth in the jaws are often irregularly arranged so that 4 rows are found in some places in both jaws. In some individual fish where teeth are regularly arranged there are 3 rows in the upper jaw and 4 rows in the lower jaw. Number of rows decreases laterally to one at the rictus. The outer row teeth are bicuspid with the lateral cusp the smaller, while inner row teeth are tricuspid, with the central cusp the most prominent. The upper jaw has more teeth than the lower jaw.

The diploid chromosome number is 2n=44, comprising 25 submetacentic, 18 subtelocentric and 1 metacentric chromosomes with an arm number of 70. The chromosome count may indicate a relationship to the Levantine Tristramella (Esmaeili et al., 2006).

Scales in upper lateral line 17(1), 18(1), 19(2), 20(8), 21(9), 22(10), 23(7), 24(4), 25(2), 26(1) or 29(1); scales in lower lateral line 9(6), 10(17), 11(14) or 12(9); total scales in lateral series 28(1), 29(2), 30(4), 31(9), 32(13), 33(5), 34(4), 35(4), 36(3) or 40(1); scales around caudal peduncle 16(15), 17(13), 18(15), 19(2) or 20(1); precaudal vertebrae 14(2), 15(53) or 16(11); caudal vertebrae 13(26), 14(35) or 15(5); total vertebrae 28(19), 29(40) or 30(7).

Dorsal fin spines 14(6), 15(46) or 16(14); dorsal fin branched rays 9(2), 10(36) or 11(28); anal fin branched rays 6(7), 7(20), 8(38) or 9(1); pectoral fin branched rays 11(42) or 12(24); and total gill rakers 14(6), 15(9), 16(24), 17(19), 18(6) or 19(1).

Sexual dimorphism

Head length is greater in females while pelvic fin length is smaller in females compared to males. Interorbital width is greater in males. Dorsal and anal fins are larger in males when expressed in terms of longest ray length in head length (Coad, 1982a). Colour differs as described below.

Colour

Live specimens are brightly coloured in spawning condition (based on aquarium photographs in Schulz (2004)). The male is brick-red on the lower sides and underside of the head with black on the dorsal head surface. The underside of the head may also be black. The belly anterior to the pelvics is black. The chin is white. The sides off the head have a few, scattered white spots but the body, dorsal and caudal fins are densely covered with white spots and blotches. Those on the dorsal fin are arranged in oblique rows and those on the caudal fin in bars. The anal fin has white spots also but these are not present distally. The pectoral fin has darkened rays but lacks spots. The pelvic fin has white spots proximally but less than the anal fin but is overall a dark black. Other reports and photographs (Svardal (2006) and Svardal and Svardal (2006)) show dominant spawning males to be black with brilliant turquoises blotches on the body but especially so on the fins. The female has an overall silvery colour with up to 9 faint to moderate flank bars. Fins are yellowish. The dorsal fin has a black tilapia-mark on the posterior dorsal fin.

Overall body colour outside the spawning season is a light lime green, with an iridescent tinge to the posterior edge of the operculum and on the back. The dorsal fin has light, lime-green, oblique bars, the last one or two black-edged and spot-like. The peritoneum is black.

Preserved specimens have the following pigmentation. Young fish have a distinct tilapia-mark, a spot on the rays of the soft dorsal fin typical of these cichlid fishes. The spot is black and is surrounded by a hyaline ring. Occasionally a second spot is found posterior to the first spot. The principal spot is often retained in adult fish. Young also have 7-11 bars along the flank which are also retained by adults but are then less distinct. In adults the dorsal fin rays and membranes are covered with melanophores interspersed with hyaline spots and irregular blotches. Wavy, oblique bars are found posteriorly on the soft dorsal fin in some specimens. The caudal fin has a series of about 7 narrow bars in some male specimens while females are uniformly grey. The anal fin is narrowly barred with up to 6 vertical to oblique bars in some specimens, in others uniformly pigmented grey proximally fading to hyaline distally. Pectoral and pelvic fins are not barred and are lightly pigmented, the pelvics being the darker. The head and body, including the belly, are more heavily pigmented to give an overall brown colour, lightest on the belly anterior to the pelvic fins in females. Scales are not pigmented on their free margins, which are pale.

Some specimens may be quite dark, particularly the back and fins and strikingly the lips.

Size

Attains 11.09 cm standard length or 12.95 cm total length (Esmaeili and Ebrahimi, 2006). Lamboj et al. (2006) give 13 cm, presumably total length.

Distribution

The cichlid is restricted to rivers draining to the Straits of Hormuz in southern Iran (Coad, 1982a; Abdoli, 2000). Svardal and Svardal (2006) also map this species at 27.770°N, 54.999°E, slightly to the north of samples mapped here. The distribution mapped by Stiassny in Keenleyside (1991) following Berra (1981) is too far north. The map in Berra (2001) is more accurate.

Specimens kindly sent to me by H. R. Esmaeili in 1997 are from the Dozdan River at 27°26'N, 57°10'E, an eastwards extension into the Minab River basin. The cichlid was not collected there in the 1970s. The new record may simply be filling in a collecting gap, a natural range extension or possibly the result of an introduction.

Zoogeography

Trewavas (1983) suggests that the ancestor of this cichlid was distributed across the Arabian Peninsula in the Late Pliocene/early Pleistocene when this area was more humid. Desiccation in the Pleistocene and Recent Periods then led to the extinction of the ancestor. A Miocene-Oligocene fossil "Tilapia" was reported from Jisan in southwest Saudi Arabia where cichlids are not now native (Brown, 1970) and would help support a southern distribution of cichlids as the origin of Iranocichla. However Trewavas (1983) reports that this fossil cannot be identified as a cichlid. Micklich and Roscher (1990) and Lippitsch and Micklich (1998) also report three species of what are presumably cichlids from southwest Saudi Arabia in the Baid Formation of Oligocene age at Ad Darb, Tihamat Asir. They belong to the basal grade of cichlids and to two different clades within the African assemblage. Whybrow and Clements (1999) record unidentified Cichlidae from the Early Oligocene from the coastal trip of Dhofar, Sultanate of Oman with a date of 33 MYA. Murray (2001) reviews these and other cichlid fossil material and the identity of Omani material as cichlids appears questionable. Southwest Saudi Arabian material is more clearly cichlid but does not point to a continuous distribution eastwards across the Arabian Peninsula. However, Bănărescu (1992b) considers that a common ancestor to Iranocichla and the Levantine Tristramella evolved in the Arabian Peninsula from African forebears in the Miocene, the latter lineage extending its range northwards to the Levant and the former eastwards to Oman and southern Iran, the Straits of Hormuz not then being in existence. Murray (2001) gives an earliest date for colonisation of Iranocichla ancestors to be the Middle Miocene when southern Iran rose above sea level. She does not consider a coastwise dispersal through brackish waters of Arabia to be a possible route as cichlids are not found there today but indicates a route through the Tethys Sea/Indian Ocean could be possible.

Coad (1982a) suggests another hypothesis. Iranocichla could be a relict of a once wider distribution across the Tigris-Euphrates basin in a northern arc rather than directly across the Arabian Peninsula. The absence of cichlids from southern Arabia today warrant this alternative hypothesis. Warm streams have probably been continually present in southern Arabia and support a limited fish fauna today. There is no apparent reason why cichlids should have become extinct there. Murray (2001) points out that Iranocichla lives at 40-400 m above sea level and is limited by mountains north of the present distribution, and so it must have arrived before the mountains attained their current height, to support Coad's hypothesis.

The headwaters of the Tigris-Euphrates basin are narrowly separated from the Levant Rift Valley today and at times in the past may have had direct exchanges of faunas (Kosswig, 1965; 1973; Krupp, 1987). The modern absence of cichlids from the Tigris-Euphrates basin may be explained by low temperatures. The effects of low temperature on Iranocichla have not been investigated but fingerlings of Tilapia aurea, which occurs naturally in the southern Levant Rift Valley, begin to die at 11°C and cease all motion at temperatures below 10°C (Chervinski and Lahav, 1976). Most of Syria, northern Iraq and the northern Arabian Peninsula have temperatures below 10°C in winter (Beaumont et al., 1976). Spot temperatures from southern Iran at the head of the Persian Gulf are about 12-13°C in January compared to 18-20°C around the Straits of Hormuz where Iranocichla occurs. Additionally the death rate of Tilapia aurea in fresh water is twice that in salt water at low temperatures: it may be pertinent that Iranocichla is found mainly in saline streams. This hypothesis can only be confirmed by fossil discoveries.

Habitat

The streams in which this species lives are subject to desiccation with continuous flow breaking up into isolated pools. The survival of cichlid populations in these pools varies between years and some pools may be fishless in one year and populated in another.

The area around the Straits of Hormuz is rich in salt domes and consequently most surface streams are saline, up to 80 mS. Cichlids are found in these streams but also in the Sar Khun oasis which is fresh with a conductivity of 1.6 mS. Apparently they can be transported at 10 mS as this is less stressful. Stream waters are cloudy to clear and colourless. Water temperatures in winter (November to March) range from 15 to 33°C and would be considerably higher in summer when air temperatures reach 45°C with no riparian shade and low water levels. Lamboj et al. (2006) and Svardal (2006) give water temperatures of 33-40°C and conductivity of 45-75 mS.

Streams are 1 to 50 m wide and consist of alternating riffles and pools with occasional backwaters. The bottom is pebbles, sand or mud. Aquatic vegetation is restricted to encrusting algae.

Kiabi and Abdoli (2000) found this species to be, with Cyprinion watsoni, the commonest in Hormozgan Province.

Age and growth

Unknown. Esmaeili and Ebrahimi (2006) give a significant length-weight relationship based on 379 fish measuring 2.74-11.09 cm standard length. The a-value was 0.0349 and the b-value 3.047 (a b-value < 3 indicating a fish that becomes less rotund as length increases and a b-value >3 indicating a fish that becomes more rotund as length increases).

Food

Gut contents of 5 specimens (41.2-90.5 mm standard length) included only algae and diatoms suggesting food is scraped from rocks and from bottom deposits. This is consistent with an elongate gut and black peritoneum. Aquarium specimens eat algal tabs but also appreciate insects and fish remains.

Reproduction

This species is a mouth brooder. A breeding female and a male were caught in a backwater on March 18 of the Mehran River (the type series). This backwater was 1-5 m wide, maximum depth was 40 cm over a mud bottom, the water was cloudy and highly saline (40mS) and temperature ranged from 26°C at the mouth of the backwater to 33°C at its head. Eggs in fish taken in November and January are small so the breeding season is deduced to be around March. Five eggs ranged in length from 3.2 to 3.8 mm, mean 3.6 mm and in width from 2.4 to 2.7, mean 2.5 mm. Total number of eggs from 2 females, 59.0-59.2 mm standard length was 36 and 38 respectively. Eggs are yellow-orange in preserved fish.

A female 116.9 mm standard length from the Mehran River had 153 larvae in her mouth, ranging in length from 9.6 to 10.9 mm (H. R. Esmaeili, pers. comm., 6 October 2005).

Schulz (2004) observed fish in the field and found each male occupying a territory defending a nest about 1 m from each neighbouring nest. The nests were made on light grey, fine sand and consisted of a pit approximately 15 cm in diameter. The pit was black because of anoxic conditions below the sand surface. The actual nest was about the same as the body length of the fish (8-10 cm) and lay at the centre of the pit. The pit was surrounded by a rim about 1.5 cm high with an internally indented margin. Simpler pits are built where building materials are unavailable. Females were present in schools in deeper water in the river centre. Individual females swam purposefully to the nest defended by the male. The male directed the female to the nest centre with folded up fins while the female spread her fins and showed radiating colour changes. Spawning occurred immediately and neighbouring males intervened continuously at a speed that did not allow full analysis of the movements. A defending male would chase away an intruding male allowing another male into the unprotected nest to mate with the female. A clutch of eggs was always inseminated by a whole group of males.

Spawning site photographs courtesy of Thomas Schulz

Parasites and predators

Unknown although piscivorous birds have been observed along the streams where the cichlid is found.

Economic importance

Saadati (1977) suggests that this salt-tolerant species could be a valuable resource if introduced into the saline and fishless waters of internal basins. However this is not advisable since the native fauna, evolved in a fishless environment, could be devastated before it has even been documented. It is now an aquarium fish in Germany (Schulz, 2002; 2004a; 2004b; Oliver Lucanus, pers. comm., 23 January 2004; Lamboj et al., 2006; Svardal, 2006; Svardal and Svardal, 2006). Articles in aquarium magazines give photographs in spawning condition, including mouth-brooding, and details for their maintenance, including water with a conductivity of 50-70mS/cm NaCl or sea salt mixture, tank water changed once a week, vegetarian food tabs (containing the blue-green alga Spirulina), and a temperature of 20-35°C, optimally 27°C. It has been noted that males, in continually defending a nest and courting, "wear out" earlier than females (Thomas Schulz, in litt., 12 October 2006).

Conservation

Axelrod (1993) states that "as pollution chokes the waters of southern Iran, we can expect this fish to disappear very quickly" and "Because of the restricted range of this fish and the continual warfare and oil pollution in the area, Iranocichla hormuzensis may well be on its way to extinction - if it is not gone already". Bailey (2006) apparently repeats this. However its habitat is mostly saline streams which cannot readily be used for agriculture or industry. The surrounding area is not industrialised, nor likely to be, and was never a war zone so pollution is not a problem for this species.

Flash floods are probably a significant problem as water drains rapidly off vegetation barren land. The scouring action may well displace or strand cichlids. Mouth brooding offers protection against floods and against associated fishes.

Svardal (2006) and Svardal and Svardal (2006) give details of capture, transport and aquarium care of this species.

Further work

Further investigations into the biology of this species are needed.

Sources

Rabbaniha (1993a, 1993b, 1994) gives Farsi accounts of this species and cichlids in general. The account is based principally on Coad (1982a).

Type material: See above, CMNFI 1979-0408A, CMNFI 1979-0408B, CMNFI 1979-0139, BM(NH) 1981.1.12:1-2,  MNHN 1981-107, 108, CAS 47324, ROM 36389 and BC 81-1.

Iranian material: CMNFI 1979-0138, 17, 25.6-97.3 mm standard length, Fars-Hormozgan border, stream in Rasul River drainage (ca. 27º32'N, ca. 54º58'30"E); CMNFI 1979-0140, 48, 24.2-59.4 mm standard length, Hormozgan, stream east of Kichal, Kul River drainage (27º14'N, 55º46'30"E); CMNFI 1979-0141, 5, 15.0-21.0 mm standard length, Hormozgan, Kul River (27º17'30"N, 56º03'30"E); CMNFI 1979-0142, 65, 21.3-82.8 mm standard length, Hormozgan, Baghu River (27º17'N, 56º28'E); CMNFI 1979-0143, 3, 25.0-26.7 mm standard length, Hormozgan, marsh in Hasan Langi River drainage (27º21'N, 56º50'30"E); CMNFI 1979-0148, 5, 33.2-92.7 mm standard length, Hormozgan, Sarzeh River (27º30'30"N, 56º15'30"E); CMNFI 1979-0181, Hormozgan, Kul River (27º17'30"N, 56º03'30"E); CMNFI 1979-0184, 12, 31.4-50.4 mm standard length, Hormozgan, effluent of Rasul River (27º11'N, 55º42'E); CMNFI 1979-0185, 7, 26.1-59.8 mm standard length, Hormozgan, stream in Rasul River drainage (27º06'N, 55º45'E); CMNFI 1979-0187, 2, 63.9-64.6 mm standard length, Hormozgan, stream at Sar Khun (27º23'30"N, 56º26'E); CMNFI 1979-0406, 5, 33.4-59.2 mm standard length, Hormozgan, stream north of Bandar-e Charak turnoff (26º48'N, 54º18'E);CMNFI 2007-0053, 17, 28.0-59.9 mm standard length, Hormozgan, Sarzeh River (ca. 27º36'N, 56º15'E); CMNFI 2007-0057, 14, 30.2-85.5 mm standard length, Hormozgan, Mehran River below Bastak (ca. 27º05'N, ca. 54º05'E); CMNFI 2007-0058, 2, 64.8-83.0 mm standard length, Fars, headwaters of Gowdar River (ca. 27º24'N, ca. 54º16'E)

Genus Oreochromis
Günther, 1889

Oreochromis niloticus
(Linnaeus, 1758)

Introduced to the Tigris River basin in Iraq but did not apparently survive winterkill (Herzog, 1969). No Iranian record. Red tilapias (Oreochromis sp.) have been studied in aquaponic systems in Iran so there is a potential for an exotic release (Rafiee and Saad, 2005).

Genus Tilapia
Smith, 1840

Tilapia zilli
(Gervais, 1848)

Introduced to the Tigris River basin in Iraq but did not apparently survive (Job, 1967). Redbelly tilapias are established in the Syrian Euphrates (R. Beck, pers. comm., 2000) and a recent report by Beshar Abd Al-Hussain Al-Saadi (in litt., 10 October 2006) of a cichlid at Al Musayyib on the Euphrates River in Iraq may well be this species. These could spread to Iranian waters. No Iranian record. The Farsi name is تيلاپيا (= tilapia).

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© Brian W. Coad (www.briancoad.com)