Genus Leucaspius
Heckel and Kner, 1858

The genus Leucaspius has not been recently revised in detail and its composition remains uncertain. There may be several species in Europe but only one has a wide distribution and this is found in Iran.

The genus is characterised by a moderately compressed and elongate body; an incomplete lateral line on up to about 13 scales; moderately large, easily detached scales; short dorsal and somewhat longer anal fin; belly without a keel but somewhat compressed; terminal mouth with lower jaw entering the depression of the upper; pharyngeal teeth usually in 2 rows; and gill rakers of moderate size and density.

Leucaspius delineatus
(Heckel, 1843)

Common names

mahi-ye riz-e noqrei or mahi-e-rize-noghreie (= small silvery fish).

[gafgaz ustuzani in Azerbaijan; ovsyanka, verkhovka, Kavkazskaya verkhovka or Caucasian verkhovka in Russian; sunbleak, white aspe, rain bleak; belica; Moderlieschen in German].

Systematics

Squalius delineatus was originally described from Wien and Mähren, Austria. The Caspian Sea basin taxon is given by Berg (1948-1949) as Leucaspius delineatus delineatus natio caucasicus Berg, 1949, described from Transcaucasia, which is distinguished by a lower average dorsal fin branched ray count (7-8 rather than 8 or rarely 9 for the typical form of Europe). This natio has no taxonomic standing but has been applied as a subspecies by some authors (Arnold and Längert, 1995).

Key characters

The large, rounded papillae around the genital opening are distinctive in females, and for both sexes the combination of an incomplete lateral line with moderately large scales is distinctive.

Morphology

Dorsal fin with 2-3, usually 3, unbranched rays followed by 7-10 branched rays (usually 8 in Europe but counts of 7 and 8 are about equally frequent in the Caucasian populations according to Berg (1948-1949) but Abdurakhmanov (1962) gives a frequency of 94% for 8 rays and only 6% for 7 rays in fish from Azerbaijan), anal fin with 3-4, usually 3, unbranched rays followed by 9-17 branched rays (10-12 in the Caucasian subspecies), pectoral fin branched rays 11-16 and pelvic fin branched rays 7-8. Lateral series scales 36-53; lateral line incomplete with 0-13 pored scales anteriorly. Scales bear few anterior and posterior radii, have few circuli, a subcentral anterior focus and are a vertical oval in shape. Gill rakers 10-17 (rarely 20, usually 13-16), reaching the second raker below when appressed. Vertebrae 36-40. Pharyngeal teeth very variable 5-5, 5-4, 4-4, 4-5, 1,5-5, 5-5,1, 1,5-4, 5-4,1, 1,4-4, 4-4,1, 1,5-5,1, 1,5-5,2, 1,4-4,1, 1,4-5,1, 1,5-4,1, 1,5-4,2, 1,4-5,2, 2,5-4,1, 2,5-4,2, 2,5-5,2 and even 2,5-6,1. The frequency of various counts varies with locality, and even whether single row counts dominate over two-rowed counts (Arnold and Längert, 1995). Teeth are hooked at the tip and slightly to strongly serrated. The belly is compressed in the mid-line between the pelvic fins and the vent but does not form a strong keel. The gut is an elongate s-shape. The chromosome number is 2n=50 (Klinkhardt et al., 1995).

Meristic values for Iranian specimens are:- branched dorsal fin rays 8(10) or 9(1); branched anal fin rays 10(4) or 11(7); branched pectoral fin rays 11(7), 12(3) or 13(1); branched pelvic fin rays 7(10) or 8(1); scales in lateral series 39(3), 40(5), 41(1), 43(1) or 45(1); total gill rakers 13 (4) or 14(7); and total vertebrae 36(1) or 37(9). One specimen showed fusions of abdominal vertebrae.

Sexual dimorphism

Females have a unique fold of skin in the shape of two, large, rounded papillae around the genital opening. The male is a little smaller than the female. Males develop prominent nuptial tubercles on the dorsal head surface, snout, on the lower jaw in three pairs and on the upper jaw in two pairs for a total of about 60 tubercles. The male genital opening is depressed.

Colour

The back is olive-green to brown and the flanks and belly silvery-white. A steel blue or bluish-green stripe begins at the rear third of the body and extends back, broadening, to the tail base. Fins are hyaline or slightly yellowish. The peritoneum is light.

Size

Attains 12 cm total length although only up to 5.6 cm total length in the Caucasian form.

Distribution

Found in western and central Europe from the Rhine and north of the Alps east to northern drainages of the Black Sea and the western and northern drainages of the Caspian Sea. Leucaspius delineatus caucasicus is found in the north Caucasus including the Black Sea parts and in Transcaucasia. In the southern Caspian Sea basin, it is found in the lower reaches of the Kura River, Imeni Kirova Bay and the Lenkoran region of Azerbaijan (Kuliev, 1989). A single specimen from Iran was collected by Mr. Akbar Nasrollazadeh near Siah Darvishan (which is at 37°22'N, 49°26'E) in Gilan on 27 May 1993. In June 1996 over 50 specimens were caught in the Anzali Mordab (= Talab) by K. Abbasi and A. Sarpanah of the Gilan Fisheries Research Centre (Iranian Fisheries Research and Training Organization Newsletter, 15:4, 1997). Also reported from the Anzali Talab by Abbasi et al. (1999) and present in the Safid River and Amirkelayeh Wetland (Nasrollazadeh, 1999; K. Abbasi, pers. comm., 2001).

Zoogeography

The Caspian shore of Iran has been surveyed in some detail during the 20th century and it is curious that this species was only discovered towards its end. It may simply have been confused with other small, silvery minnows although it should be noted that some of the surveys were carried out by Russian workers familiar with this species. It may be a recent introduction with other, commercial exotics, and therefore may not be from a Caucasian population.

Habitat

Found in still or slowly flowing water with vegetated shores in large schools. It can be found in fish ponds, ditches, gravel pits and quarries as well as natural habitats. Still water is required for reproduction. It is tolerant of a wide range of temperatures, pH and salinity depending on adaptation, e.g. temperature range of 3-32.8°C (Arnold and Längert, 1995). This small fish is found in large schools near the water surface. It may appear in small ponds without any apparent connection to other water bodies, hence the German name that has been interpreted as "Moderlieschen" or motherless. However, the German name may more correctly mean mud lover (G. H. Copp, in litt., 16 June 2004).

Age and growth

Life span is about 4-6 years with growth fairly continuous over this period.

Food

Diet comprises plankton such as cladocerans, copepods and rotifers, benthic chironomids, flying insects which land on the water surface, and also some algae and detritus.

Reproduction

There is often a spawning migration against the water flow (up to 2-3 m/sec) to new waters. Eggs are laid in strings which are wound spirally around plants by the female, aided by the fold of skin around the genital opening. They may also be laid in a disc-shaped patch on any flat surface. Several spawnings occur over a few weeks in March to September in Europe. The eggs are guarded and fanned by the male who covers them with a bacteriostatic dermal mucus. Up to 485 eggs are found in females and have diameters up to 0.5 mm in Azerbaijan, up to 3500 eggs and 1.5 mm in Europe. Maximum egg production over two seasons is about 500-600 (Abdurakhmanov, 1962). Clutch sizes are about 50-350 eggs (Arnold and Längert, 1995). A minimum temperature of 18°C is required for reproduction.

Parasites and predators

None reported from Iran but eaten by a wide variety of other fishes in Europe and numerous parasites reported (Arnold and Längert, 1995).

Economic importance

The scales have been used in the production of artificial pearls as with Alburnus alburnus. It has also been used in aquaria and garden ponds and as bait by anglers.

Conservation

Lelek (1987) classifies this species as rare to vulnerable in Europe. Kiabi et al. (1999) consider this species to be conservation dependent in the south Caspian Sea basin according to IUCN criteria. Criteria include few in numbers, habitat destruction, limited range (less than 25% of water bodies), absent in other water bodies in Iran, present outside the Caspian Sea basin.

Further work

More specimens from Iranian waters need to be examined to determine if this species belongs to a distinct subspecies or is an exotic population of the European type subspecies. Biology of the Caucasian subspecies is unknown.

Sources

Arnold and Längert (1995) summarise biology of European populations in detail.

Iranian material: Uncatalogued material, 11, 31.2-37.5 mm standard length, Gilan, swamp near Hendeh Khaleh (37º23'N, 49º28'E).

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