This family is known as the snakeheads or serpent-heads because of the characteristic broad head with large scales and a large oblique mouth. They are found from Africa to eastern Siberia and Southeast Asia and comprise about 29 species but the family is need of a revision. Maximum size is about 1.2 m.

Snakeheads are characterised by paired accessory organs or suprabranchial organs in the upper gill chamber (above and behind the gills) which enable these fishes to breathe air, survive low oxygen conditions and even reputedly travel overland; an elongate rounded body becoming compressed posteriorly; the dorsal and anal fins are long and of even height, and spineless; pelvic fins are present or absent; the mouth is large and the lower jaw protrudes; there are teeth on the jaws, vomer and palatines; gill openings are wide and the gill membranes are united but free from the isthmus; branchiostegal rays number 5; the caudal fin is rounded; scales are small and cycloid or ctenoid; and colour is highly variable, rapidly changing to suit the surroundings.

Snakeheads are ambush predators, living in still waters although some inhabit the larger rivers. Most species build a bubble nest in vegetation, laying and fertilising the eggs below it so that they float up into the bubbles. Others are mouth brooders. One or both adults guard the nest and young and will attack intruders savagely, including humans according to folklore. Many species are known to aestivate in summer when the habitat dries. They can be carried alive wrapped in wet cloths or vegetation and may be introduced into areas outside their natural distribution.

A number of species grow large enough to be an important food in Southeast Asia but are also pests, eating more valuable species. Some species are popular in the aquarium trade. Juveniles may be called, incorrectly, "larvae" in the aquarium trade and are brighter in colour than adults.

Genus Channa
Scopoli, 1777

Channa Scopoli, 1777 has priority over Ophicephalus Bloch, 1793 (Eschmeyer, 1990). Ophiocephalus is an incorrect emendation. See also Myers and Shapovalov (1931-1932), DeWitt (1960), Ettrich and Schmidt (1989) and Pethiyagoda (1991) for discussions on the taxonomy of this genus and species.

The characters listed under the family above obtain for the genus which has only one confirmed Iranian species.

Channa argus
(Cantor, 1842)

Reported as Channa argus warpachowskii (Berg, 1909) from the Karakum Canal and Kopetdag Reservoir in Turkmenistan as an exotic from China (Shakirova and Sukhanova, 1994; Sal'nikov, 1995). This canal connects with the Tedzhen River basin shared with Iran and ultimately may connect with the Caspian Sea basin. No Iranian record.

Channa gachua
(Hamilton-Buchanan, 1822)

Common names

mahi-ye sarmari (= snakeheaded fish).

[tond, dolli or dauli in Pakistan; dwarf snakehead, frog snakehead, brown snakehead, oriental snakehead, smooth-breasted snakehead].

Systematics

Ophicephalus gachua was originally described from Bengal, India. Possible syntypes are in the Natural History Museum, London under BM(NH) 1858.8.15.54 (1) and BM(NH) 1858.8.15.144 (1) (Eschmeyer's "Catalog of Fishes", downloaded 29 August 2007).

Key characters

The large head scales and elongate dorsal and anal fins are distinctive.

Morphology

Dorsal fin rays 30-37 (the last 2 rays counted as 1 where close together at base), anal fin rays 20-24, pectoral rays 13-16, and lateral line scales 39-47. Pelvic fins may be present or absent. The lateral line is displaced down one row under, or just beyond, the posterior end of the pectoral fin. Scales have a vertical anterior margin, parallel dorsal and ventral margins and a rounded posterior margin. The anterior dorsal and ventral corners are square cut, rounded to sharp. Circuli are fine and numerous on the anterior field but on the posterior field become coarser and are parallel to the horizontal axis. Radii are numerous in the anterior field and radiate from a central focus. Gill rakers are minute. The gut is short and s-shaped. The anterior nostril is tube-shaped and hangs over the upper lip to the mouth. The chromosome number is 2n=78 (Banerjee et al., 1988; Klinkhardt et al., 1995).

Meristic values for Iranian specimens are:- dorsal fin rays 33(1), 34(3) or 35(1) (the last 2 rays counted as 1 where close together at base); anal fin rays 22(5); pectoral rays 14(3), 15(1) or 16(1); and lateral line scales 41(2), 43(2) and 44(1).

Sexual dimorphism

Females have a dark eye-spot at the posterior part of the dorsal fin (Pethiyagoda, 1991).

Colour

Colour varies with the habitat. The back is usually greenish-grey to brownish with bluish tints and the flank is crossed by irregular oblique bars, less obvious in adults than young. The background colour of the flank is dove grey with a violet sheen in males. The dorsal, anal and caudal fins are slate-coloured and have characteristic, narrow and strong orange margins (white in preservative). The membranes of these fins may be an iridescent green. The dorsal fin may have a blue or bluish-green stripe with a vertical extent from the fin mid-point distally about half-way to the fin margin on the membranes. The caudal fin has blue and green rays. Females have a dark eye-spot at the end of the dorsal fin. The pectoral fin base is dark blue and there are 4-5 orange and blue bands on the fin, with the margin orange. Bars on the pectoral fin are very distinctive in preservative, alternating dark and light. The iris is reddish. The peritoneum is silvery.

Size

Attains 33 cm (Day, 1875-1878) although Courtenay and Williams (2004) give 17 cm, probably more accurate given taxonomic confusion in the past.

Distribution

Reported from the Dasht and Rakshan rivers, the Makran coast and the Mashkel (= Mashkid) River basin in Pakistan (Zugmayer, 1913). Iranian records were limited to 4 specimens collected by N. A. Zarudnyi in the Bampur river (upper or middle course) during 15-23 July 1898 (27 June-4 July in Berg (1949)) until 1 specimen was found in the Halil River basin near Sabzeveran at 28°39'N, 57°45'E, over 300 km northwest of the Bampur River at Bampur (Coad, 1979a). Abdoli (2000) reports this species from the Halil and questionably from the Iranian Makran. Ebrahimi (2001) maps two localities in the Halil River. The map in Berra (2001) has this species too close to the Straits of Hormuz and the map in Courtenay and Williams (2004) does not extend far enough into Iran.

Zoogeography

The distribution of this species in southeastern Iran is confirmed in Coad (1979a), a record not noted by Bănărescu (1992b). It is the westernmost occurrence of the species in Asia. It is found eastwards to Indonesia (Ettrich and Schmidt, 1989).

Habitat

This species can survive in turbid and poorly oxygenated water because of its ability to breathe air. Air breathing is so well developed that this snakehead can travel overland between water bodies, using a hopping motion. Two pharyngeal suprabranchial cavities extend along the body to the caudal peduncle and are lined with vascularized mucous membranes. Mountain streams, rivers, lakes, reservoirs, ponds, rice paddies and even hot springs are recorded as habitats for this species in South Asia. Clear water in shallow streams and swamps in forested areas are preferred (Courtenay and Willimas, 2004) while Pethiyagoda (1991) states that flowing water is preferred. It is found in mud among emergent vegetation in Sri Lanka (De Silva, 1991). It may be largely nocturnal. This species can survive temperatures as low as 13°C, a pH range of 3.1-9.6, brackish water, and waters low in calcium, low in mineral content and pronounced anion excess (Lee and Ng, 1994). Low temperatures may be a limiting factor in its distribution in Iran.

Age and growth

Some populations in mountain streams are mature at about 13 cm while in lower areas maturity is reached at about 10.2 cm at 20 months. The population examined in Sri Lanka has 90% of the individuals less than 24 months old and 99% less than 38 months. Longevity is about 6 years (De Silva, 1991).

Food

This species is recorded as a nocturnal predator on other fishes and on frogs but most diet studies indicate that insects and crustaceans are the main foods (De Silva, 1991; Pethiyagoda, 1991). Young fish feed on unfertilised eggs from the mother for about 4 weeks. These eggs are released and fall in the water (while those which hatch float). The young stimulate egg release through close body contact with the mother, who swims in a circle while releasing the eggs. In aquaria, a female will take Artemia nauplii into its mouth and swim over to the male which releases the young to feed on the nauplii as they are emitted from behind the gill cover (Ettrich and Schmidt, 1989). An Iranian specimen had only sand grains in its gut.

Reproduction

Spawning takes place over silt or gravel bottoms or in areas of cleared vegetation forming a "nest". Vegetation is cleared by fin movements and can be 15 cm across (Ettrich and Schmidt, 1989). Some reports have the female swimming belly up and the male then fertilises the eggs as they are released by swimming diagonally over the female's vent. Ettrich and Schmidt (1989) state that the male forms a loop around the belly region of the female, an intensive and long-lasting process. This occurs after pair-bonding lasting several weeks which serves to synchronise reproduction, necessary since all the eggs are released at once. The male picks up the eggs in his mouth and keeps them there for 4-5 days until hatching (Ettrich, 1989; Pethiyagoda, 1991), as the eggs are oily and slowly float to the surface. The fry may also be protected in the male's mouth for up to three days before releasing them, but retain the fry behind the gill cover when danger threatens or night descends (Ettrich and Schmidt, 1989). Egg numbers vary between 20 and 200 per spawning (Lee and Ng, 1994). Fecundity ranges from 389 and 7194 ((De Silva, 1991; Courtenay and Williams, 2004). Brood size (97-343 larvae) is smaller than the number of mature eggs reported for females according to De Silva (1991) and many eggs either fail to develop or are lost to predators despite parental care. An Iranian fish caught on 6 May contained small and possibly atretic eggs. Egg diameter is 2.6 mm and the eggs are a golden yellow.

Ettrich and Schmidt (1989) report that 6 days after being released from the mouth, the fry ascend to the water surface and draw air. A foam nest is produced under which the young fish hide.

De Silva (1991) found breeding to take place throughout the year in Sri Lanka, with enhanced breeding in May to July and October to December. In the Karnataka State, India this species breeds from May to August. Individuals appear to spawn once in each rainy season in Sri Lanka.

Parasites and predators

None reported from Iran.

Economic importance

This species is too rare in Iran to be of any economic importance but in Sri Lanka it consumes pests in rice paddies (De Silva, 1991) and in Singapore in 1990 sold for up to Singaporean $60 (Courtenay and Willimas, 2004).

Conservation

This species would be difficult to conserve in Iran as it is rare and at its extreme westernmost distribution. Survivability may be marginal and numbers low.

Further work

Surveys to determine the distribution of this species, its numbers and its environmental requirements may enable conservation to be effective.

Sources

Iranian material: ZISP 11714, 4, 42.9-70.2 mm standard length, Baluchestan, Bampur River (no other locality data); CMNFI 1979-0220, 1, 110.9 mm standard length, Kerman, irrigation ditch, 2 km south of Jiroft (= Sabzeveran) (28°39'N, 57°45'E).

Comparative material: BC 66-32, 2, 63.8-71.5 mm standard length, East Pakistan, Chittagong Hill Tracts, Karnaphuli Reservoir tributary (no other locality data); BC 66-38, 23, 79.5-124.9 mm standard length, East Pakistan, Dacca, Bellabor Fish Market (no other locality data); BC 66-44, 2, 109-6-122.3 mm standard length, East Pakistan, Tipperali, Chandpur (no other locality data).

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