Genus Pseudorasbora
Bleeker, 1859

This genus contains 3 species with a native distribution in eastern Asia including the Amur River basin shared between Russia and China, in Japan, other parts of China, and in Korea. One species is an exotic now found in Europe and accidentally introduced in Iran.

The genus is characterised by a small and transverse mouth positioned at the top of the snout rather than the anterior tip, the lower jaw has a trenchant edge and projects slightly beyond the upper jaw, no barbels, pharyngeal teeth are in a single row, the gut is short, scales are large, gill rakers are rudimentary, dorsal and anal fins are short and spineless, and there is no keel on the abdomen.

Pseudorasbora parva
(Temminck and Schlegel in Siebold, 1842)

Common names

آمورچه (amurcheh or amorcheh), amoornama, parva.

[stone moroko, topmouth gudgeon, topmouth minnow, false rasbora; chebachek or Amur chebachok in Russian].

Systematics

Leuciscus parvus was originally described from Nagasaki, Japan.

Subspecies have been described in China but exotic introductions are usually referred to the type subspecies. Reshetnikov et al. (1997) and Bănărescu in Bănărescu (1999) give the date for this species as 1846.

Key characters

The mouth structure is unique, being very small and lying entirely before the nostril level, almost vertical, opening antero-dorsally with the gape entirely visible in dorsal view. The lower jaw protrudes to form the most anterior part of the head.

Morphology

Dorsal fin unbranched rays 3 followed by 7-8, usually 7, branched rays, anal fin with 2-3, usually 3, unbranched rays and 5-7 branched rays, usually 6, pectoral fin branched rays 11-14, and pelvic fin branched rays 6-8, usually 7. Lateral line scales 30-40, with the lateral line rarely incomplete. A pelvic axillary scale is present. The scale radii are restricted to the posterior field. Gill rakers are rudimentary and are only well-developed at the junction of the upper and lower arms of the gill arch. These rakers are stubby and rounded, reaching the adjacent raker when appressed, and bearing fine, fleshy fimbriae which extend onto the adjacent parts of the gill arch. Anterior rakers are absent and patches of fimbriae are found. Rakers number 6-16, usually 9-13. Total vertebrae 31-38 presumably the result of different counting methods; Naseka (1996) gives 36-38 and fish from Turkey have 34-37, cf. below. Pharyngeal teeth usually 5-5, rarely 6-5, with the tips strongly hooked and the area below the hook flattened and without ridges or only very weakly ridged on some teeth. The gut is an elongate s-shape. The chromosome number is 2n=50 (Klinkhardt et al., 1995).

Meristic values for Iranian specimens are:- dorsal fin branched rays 7(11) or 8(1), anal fin branched rays 6(12), pectoral fin branched rays 13(7) or 14(5), pelvic fin branched rays 7(4) or 8(8), lateral line scales 34(4), 35(5) or 36(3), pharyngeal teeth 5-5(9), 6-5(2) or 4-4(1), and total vertebrae 34(2) or 35(10).

Sexual dimorphism

A horny pad develops on the jaws in males and females during spawning and strong, sharp tubercles in males. One tubercle is found between the eye and the nostril, one below the nostril (this may be absent), one next to the upper lip on a line across from the one below the nostril, 5-8 in a row from the extreme corner of the mouth along the side of the head over the flesh of the cheek, and 2-3 below the lower lip from the tip of the lower jaw to the end of the jaw on the lower head surface. Lower head surface tubercles may coalesce at the base but each tubercle bears a single rounded cusp. Rarely a tubercle may have a single base but two cusps.

Males are larger than females and have larger fins. Spawning males are darker than females and the flank has a metallic violet sheen.

Colour

The head and body has a mid-lateral stripe but this is obscured in adults by crescentic speckles situated posteriorly on each scale. The back is light grey, the flanks silvery and the belly whitish. Dorsal and anal fins are speckled and turn almost black in spawning fish.

Preserved fish have a cream coloured belly with the back much darker. The head is black dorsally and fades to cream ventrally. The scales on the back and flanks, but not the belly, carry a broad band of pigment which follows the scale margin distally. The extreme edge of the scale is hyaline but the arc of pigment effectively defines the posterior scale margin and outlines the scale pattern of the back and flanks. Pigmentation on fins is mostly restricted to the rays and their margins but is found also on fin membranes to varying extents. Pigmentation is strongest distally on all fins. The dorsal fin, particularly in smaller fish, bears patches on the membranes posterior to branched rays 1 or 2 through 5 or 6, starting on ray 1 or 2 below the mid-point of the ray length and descending gradually behind successive rays to lie near the base behind the last ray. These patches are vertically short and do not touch the succeeding ray. The leading edge of the dorsal, anal, pectoral and pelvic fins and the upper and lower edges of the caudal fin are black in large, and some small, fish. Pigment may be concentrated along the mid-line forming a thin stripe, only apparent posteriorly in some fish. There is a dark line along the mid-line of the back. The peritoneum is silvery with some scattered melanophores.

Size

Attains 12.0 cm (Movchan and Kozlov, 1978).

Distribution

The natural range of this species is in eastern Asia as given above under the genus. It has been introduced to Iran by accident (Abdoli, 1992; Coad and Abdoli, 1993b). It is now found in ab-bandans at Avaness, Hasan Tabeeb and Shaeed Ziaee (all about 40-45 km east of Gorgan), Teer Tash and Lemrask (about 20-25 km east of Behshahr), Lapoo (about 4 km east of Babol Sar) on the Caspian Sea coast, and at Gorgan-Aliabad, Mazandaran, from the Safid River estuary and neighbouring waters and the Anzali Talab (Iranian Fisheries Research and Training Organization Newsletter, 6:8, 1994; Anonymous, 1994; Abbasi et al., 1999), from the Atrak, Gorgan, Gharasu, Tajan, Babol, Haraz, Sardab, Pol-e Rud, and Safid rivers (Kiabi et al., 1999), from fish ponds at Arak probably inadvertently carried there with carp fingerlings imported from Gilan on the Caspian shore; at Mashhad in northeastern Iran, in springs near Kermanshah and in Lake Zeribar, Kordestan (Coad, 1996g); in Sistan at Hamun Kushk, and the canal flowing into the Chahnimeh (J. Holčík, in litt., 1996), and from the International Wetlands of Alma-Gol, Adji-Gol and Ala-Gol (Patimar et al., 2002a; 2002b).

Abdoli (2000) records it generally from the Kavir, Lut, Yazd and Sistan basins; the lower Kashaf River in the Tedzhen River basin; the middle Atrek, lower Neka, Babol, Heraz, Chalus, Tonekabon, and Safid rivers and the Anzali Talab in the Caspian Sea basin; the middle to lower Talkheh and lower Zarrineh rivers in the Orumiyeh basin; the lower Shur and middle and lower Qareh Chai in the Namak Lake basin; the middle and lower Zayandeh River in the Esfahan basin; and the Simarreh and lower Gav Masiab rivers in the Tigris River basin. Jolodar and Abdoli (2004) record it from most water bodies on the Iranian Caspian coast.

It is also recorded in the Karakum Canal, Kopetdag Reservoir and Tedzhen River of Turkmenistan (Shakirova and Sukhanova, 1994; Sal'nikov, 1995) so may well reach the Tedzhen (= Hari) River basin of Iran eventually. Pipoyan (1996a) reports it from the Araks River in Armenia.

Zoogeography

This species was first recorded in western Eurasia in Romania in 1960 as an accidental introduction with Chinese carps from the lower Yangtze River of China. The species is now widespread in Europe and is becoming common in western Asia including Kazakhstan, Uzbekistan, Kyrgyzstan and southern Anatolian Turkey as well as Iran (Wildekamp et al., 1997).

Habitat

This species prefers well-vegetated areas as protection from predators. It may be found in streams, rivers and ponds, and more rarely in the shallows of large lakes. It is apparently quite resistant to pollution (Bănărescu in Bănărescu, 1999) and is found in waters that freeze over and that attain 30ºC in summer (Boltachev et al., 2006).

Age and growth

Life span is about 5 years with maturity attained at 1-2 years, usually at 1 year in Europe or the second year of life in the Crimea (Boltachev et al., 2006). Most fish in a population are 2-3 years old or 1-2 years in the Crimea. Patimar et al. (2002a; 2002b) report 4 age groups from the International Wetlands of Alma-Gol, Adji-Gol and Ala-Gol, with the smallest mature specimens found at 2 years. Esmaeili and Ebrahimi (2006) give a significant length-weight relationship based on 33 Iranian fish measuring 3.29-5.99 cm standard length. The a-value was 0.0286 and the b-value 2.763 (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

This species feeds on benthos but also some zooplankton. Food items include various aquatic insects such as stone flies, caddis flies, chironomids, water sawbugs and midge larvae but guts also contain sponges, bryozoans, Spirogyra, detritus, and fragments of higher plants (Movchan and Kozlov, 1978). It may also feed on the eggs and juveniles of native fishes. Young fish take zooplankton (Movchan and Kozlov, 1978). Bănărescu in Bănărescu (1999) reports also isopods and aquatic worms and, in fish ponds, artificial food.

Reproduction

Reproduction begins at 16-18°C and lasts two months in its native Amur River basin. Fecundity is about 5000 elliptical eggs with a diameter of 2.0-2.5 mm, and this species has intermittent spawning with up to 85 eggs per batch in introduced populations in Central Asia (Makeyeva and Mokhamed, 1982). Up to 60 batches may be laid in a spawning season. The spawning site is cleaned of ooze and plant material. Adhesive eggs are deposited on the lower surface of stones, and occasionally sticks or empty mollusc shells, and are protected by the male using the head tubercles to drive away other fishes. The ellipsoidal eggs are laid in strips, usually of 5 eggs but as many as 10. Males clean the eggs and remove dead ones. The spawning season in Central Asia is April to August and spawning takes place in warm, shallow and calm waters in the morning. Spawning in the Crimea is in second half of May or in June, late May to July in the Ukraine and from the end of June to the beginning of August in the Amur (Boltachev et al., 2006). Female specimens from Iran collected in March, April and May are ripe and males have well-developed breeding tubercles and Patimar et al. (2002a; 2002b) report a spawning peak in April in the International Wetlands of Alma-Gol, Adji-Gol and Ala-Gol of Iran.

Parasites and predators

Malek and Mobedi (2001) report Clinostomum complanatum from this species in Mazandaran, in the Shiroud. Sander lucioperca and Silurus glanis are predators in Turkmenistan (Aliev et al. (1988).

Economic importance

Makeyeva and Mokhamed (1982) and Movchan and Kozlov (1978) report competition with commercial species and predatory behaviour on carp larvae if there is insufficient food. Male reproductive aggression may inhibit breeding of native fishes. Boltachev et al. (2006) report that it is a facultative parasite of other fishes in enclosed areas including commercial species such as the silver carp (Hypopthalmichthys molitrix). Areas of the body are attacked such as behind the dorsal fin and above the anal fin out of sight of the affected fish. Skin and muscles are eaten away. Welcomme in Courtenay and Stauffer (1984) regards this species as a pest when introduced. Bănărescu in Bănărescu (1999) reports this species as a competitor for food with native species in Europe.

Robins et al. (1991) list this species as important to North Americans. Importance is based on its use in textbooks.

Conservation

None required for an introduced species.

Further work

The distribution of his species as an exotic in Iran should be thoroughly documented and its biology and effects on native species studied.

Sources

Iranian material: CMNFI 1991-0160, 3, 47.8-55.8 mm standard length, Mazandaran, Abgeere Avanes (37º03'N, 54º47'E); CMNFI 1991-0161, 1, 52.5 mm standard length, Mazandaran, Madarso River (37º23'N, 55º47'E); CMNFI 1993-0134, 7, 45.0-59.1 mm standard length, Mazandaran, Gorgan-Aliabad (37º01'30"N, 54º47'36"E); uncatalogued material, 1, 86.9 mm standard length, Kermanshahan, sarabs near Kermanshah (no other locality data).

Comparative material: CMNFI 1983-0204, 7, 51.7-76.6 mm standard length, Turkey, Edirne, Meriç River at Ipsala (40º55'N, 26º23'E); CMNFI 1983-0343, 5, 49.9-83.4 mm standard length, same locality as preceding.

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