The spiny eel family is found principally in fresh waters of tropical Africa and eastwards to Korea and Malaysia. The distribution mapped by Berra (2001) extends too far into central Iran. There are about 73 species. Maximum length is less than 1 m.

The family is characterised by an very elongate, compressed or sub-cylindrical body; minute cycloid scales or body naked; a non-protractile mouth; gill opening a slit; an elongate snout with a sensitive tip flanked by tubular anterior nostrils, the posterior nostrils are hence far to the rear; long dorsal and anal soft fins (30-131 rays), dorsal soft fin preceded by usually numerous isolated spines (9-42); anal fin preceded by 2-3 spines; pectoral fin present with 12-27 rays but pelvic fin absent; caudal fin short and confluent with the dorsal and anal fins or only separated narrowly; 60-110 vertebrae; no pseudobranchiae; 2 pyloric caeca; and swimbladder present.

Some species are food fishes and they regularly appear in the aquarium trade as they are brightly coloured with distinctive patterns. They may burrow in mud and even survive some drying in ponds through their air-breathing ability. Their eel-like shape is reflected in a wriggling behaviour when handled and some are known to move backwards to impale the hand. They are found at high altitudes as well as in lowlands, in both still and running waters, often in rocky crevices or in vegetation near banks, and they emerge particularly at night to feed on prey. The rostral appendage is used to detect the prey by touch and the prey is rapidly inhaled.

Genus Mastacembelus
Scopoli, 1777

This spiny eel genus is found from the Levant to Southeast Asia. There is 1 species in Southwest Asia. Heckel (1846-1849a) misspells the genus name Mastacacemblus.

The genus is characterised by a moderate to large size, an elongate and compressed body, inferior mouth with a narrow cleft, small eyes, the absence of eye spots on the soft dorsal fin, the absence of striations under the snout, 6 branchiostegal rays, preopercle spiny or not at its postero-ventral corner, preorbital spine present, scales minute and cycloid, elongate swimbladder, lateral line present, minute jaw and palate teeth, and a rounded caudal fin.

Mastacembelus mastacembelus
(Banks and Solander in Russell, 1794)

Common names

مارماهي (= mar mahi, meaning snake fish), marmahi-ye khardar (= snake fish with spines or spiny snakefish), مارماهي شاخدار (= mar mahi shakhdar).

[salbouh abu-el-sian, salbu-al-sayan, saebouh abou siyan; abu salmabah; simack, englisi or englese at Aleppo, marmaritch or marmarij at Mosul, all in Arabic; Mesopotamian spiny eel, Euphrates spiny eel].

Systematics

Ophidium Mastacembelus was originally described from "Aleppo" and from the "River Kowick" (= Quwayq).

Ophidium Simack Walbaum, 1792 (non-binomial), Rhynchobdella haleppensis Bloch and Schneider, 1801 and Mastacembelus syriacus Gronow in Gray, 1854 are synonyms. Mastacembelus aleppensis Günther, 1861 is an unjustified emendation of haleppensis (Eschmeyer et al., 1996). Wheeler (1956) and Sufi (1957) discuss the names of this species more fully.

Three syntypes of Ophidium Mastacembelus from "Aleppo" are in the Natural History Museum, London under BM(NH) 1955.6.25:4-6, measuring 289.5-544.0 mm standard length.

Key characters

The eel-like body with 30-35 short, sharp dorsal spines, long soft dorsal and anal fins and the unique flexible snout flanked by tubular nostrils distinguish this species from all other Iranian fishes.

Morphology

The mouth gape extends back as far as the anterior eye margin or somewhat forward of this point. The posterior nostril is slit-like. The structure of the elongated eye, typical of streamlined forms, has been described by Jasim (1998) based on Iraqi specimens. The regular, mosaic pattern of the retina is associated with fishes that search for their food and the double cone structure may be associated with detection of moving prey.

Soft dorsal rays 68-90, soft anal rays 70-90 after 3 spines, pectoral rays 19-24. The penultimate spine in the dorsal fin is the longest and the central anal spine is the longest. Iranian specimens had 31(2), 32(6) or 33(4) dorsal fin spines, 19(5) or 20(3) pectoral fin branched rays, and total vertebrae 86(1), 87(1). The diploid chromosome number is 2n=48, arms number NF=88 and there are 11 metacentric, 9 submetacentric and 4 subtelocentric chromosome pairs (Esmaeili et al., 2006).

Scales minute but covering the whole body, under the eye, below the posterior nostril and between this nostril and the maxilla. Each scale has a central to anterior focus with radii on all fields and an oval shape. There is a strong preorbital spine under the eye, present in some fish but concealed under the skin or absent in others. Teeth form broad bands in both jaws with the outermost teeth the largest. There are no gill rakers but spinulose patches lying flat on the arch. The gut is an elongate s-shape.

Sexual dimorphism

Unknown.

Colour

The body is blotched and barred, often forming a reticulate pattern, or a series of mid-flank blotches most evident posteriorly and sometimes running together as a stripe anteriorly. Flank blotches may form up to 17 bars running from the dorsal to the anal fin across the flank. The back is blackish to brown, olive, greyish or blue-grey, the lower flank is spotted yellow or is yellow overall and the belly is white to yellowish. A series of about 20-24 black to blackish-brown, oval spots ringed with a lighter brown follow a dark, broad but irregular stripe on the head and anterior back in the mid-line. Dorsal, anal and caudal fins are yellowish with the dorsal and caudal fins finely barred and the anal fin continuing the pattern on the adjacent body. The anal fin may be almost immaculate. The soft dorsal fin may have vermiculations rather than bars. The pectoral fins are yellowish and are finely barred. The peritoneum is brownish, with numerous fine melanophores. Small fish (about 7.7 cm total length) can be an almost uniform grey-brown to brown-green, with yellowish brown on the fins and the tail region, and fin spots are dark to absent. There is a thin bar extending vertically down or obliquely back from the eye.

Size

Reaches 58.4 cm total length, probably larger to almost 1 m.

Distribution

Found in the Quwayq, Orontes and Tigris-Euphrates basins. In Iran its is recorded from the Tigris River, Gulf and Kor River basins including the Dalaki River (Löffler, 1957; Abzeeyan, 5(5):III, 1994; Gh. Izadpanahi, pers. comm., 1995).

The record of Mastacembelus armatus (Lacepède, 1800) reported by Mokhayer (1981b) from the Kor River basin is probably a mis-identified Mastacembelus mastacembelus.

Abdoli (2000) maps this species from the Kor and Pulvar rivers of the Kor River basin; the middle and lower Shur River tributary of the Dasht-e Palang, the upper Mand and Qara Agaj, the middle and upper Hilleh and the upper Zohreh rivers of the Gulf basin; the Jarrahi, lower Karun, middle and lower Dez, Karkheh, Simarreh and lower Kashkan rivers of the Tigris River basin.

Zoogeography

This species is now known to occur outside the Tigris-Euphrates and Quwayq basins in Southwest Asia in contrast to Banister's assertion (1980). The distribution of this species is not, however, continuous across Iran as shown in a figure by Travers (1984b) mis-quoting Coad (1979, actually 1980a). It appears to be absent from the saline rivers draining to the Straits of Hormuz and from Baluchestan.

Habitat

This species is known from both lotic and lentic environments (Pazira et al., 2005). Sufi (1957) described mastacembelids as usually lurking in rock crevices or among stumps of plants near the bank and I have observed them at Lake Parishan (= Famur) inhabiting crevices of a submerged rock wall. They may be able to survive desiccation by burying themselves in mud. They are not commonly caught with nets and may be mostly nocturnal in habits. In the Marun River below Behbehan, Khuzestan this species is very common, commoner then any other site sampled in this province, possibly the result of pollution-enriched water (field sample; H. R. Alizadeh, pers. comm., 2000). In areas under human influence in Lorestan, such as the lower reaches of rivers and near cities, it is more common than in higher, pristine waters.

Age and growth

In the Helleh and Dalaki river basins of southern Iran, the condition factor of this species was 0.162-0.458 (mean 0.296) for females and 0.162-0.386 (mean 0.289) for males. Condition factor = 0.374 - 0.004 total length. Life span was up to 6 years although most fish were 3 years or younger. Females grew rapidly to age 3, after which annual growth decreased. von Bertalanffy length-at-age equations were L_t = 873.4 (1-exp{-0.082[t + 1.488]}) for females and L_t = 923 (1-exp{-0.081[t + 1.464]}) for males (Pazira et al., 2005).

Food

The flexible snout is used for sniffing out food but the eye structure suggests a visually feeding fish also. Food is assumed to include invertebrates but two fish from Iran contained fish scales and fish skeletal remains. Other species are known to eat fish eggs and fry. Food in the Hawr al Hawizah, Iraq in 2005-2006 was 55.0% shrimps and 45.0% fish and in the Al Kaba'ish (= Chabaish) Marsh entirely fish (Hussain et al., 2006).

Reproduction

Fish taken on 26 November have small but developing eggs, suggestive of spring spawning. Şahinöz et al. (2006) give details of development of embryos and artificial breeding, based on fish taken from Ataturk Dam Lake in Turkey. They obtained a fertilisation rate of 80%, egg diameters reached 2.015 mm, and hatched larvae were observed at 85 h after insemination.

Parasites and predators

Predators might find this species difficult to swallow. The row of dorsal spines are very sharp and can severely lacerate the hand when this fish is picked up carelessly. Mokhayer (1981b) records a heavy infestation with Contracaecum larvae in Lake Parishan near Kazerun. Jalali et al. (2002) and Jalali and Barzegar (2006) record Diplostomum spathaceum, Trichodina pediculus, Ichthyophthirius multifilis, Mastacembelocleidus heteranchorus, two species of Argulus, Lernaea cyprinacea, a Polyonchobothrium species and an Ancyrocephalus sp. from this species in Lake Zarivar.

Economic importance

Russell (1794) reported that this fish was "found in great abundance" and "esteemed a lighter and more delicate food" than the eel at Aleppo but it does not seem to be so common in Iran or used generally as food. Heckel (1846-1849a) gives the common name "englisi" because it was highly prized by Europeans at Aleppo. Foreign soldiers have caught this species by angling at Baghdad (www.carpecapio.com, downloaded 26 August 2005).

Conservation

This species appears to thrive in polluted areas and is not commonly caught or utilised. Its conservation status has not been assessed in field studies but it is probably not under any threat. Critically endangered in Turkey (Fricke et al., 2007).

Further work

The biology of this species needs further investigation. An assessment of its conservation status could be carried out as its somewhat cryptic nature makes its numbers difficult to determine.

Sources

Type material:- See above (BM(NH) 1955.6.25:4-6).

Iranian material: CMNFI 1979-0029, 1, 148.0 mm standard length, Fars, Dalaki River (no other locality data); CMNFI 1979-0075, 1, 252.0 mm standard length, Fars, Mand River at Pol-e Kavar (29º11'N, 52º41'E); CMNFI 1979-0124, 1, 436.0 mm standard length, Fars, Mand River at Shahr-e Khafr (28º56'N, 53º14'E); ZSM 21831, 1, 584.5 mm standard length, Khuzestan, Harmaleh on Dez River (31º57'N, 48º34'E); ZSM 26629, 1, 154.4 mm standard length, Kordestan, Lake Zaribar (35º32'N, 46º08'E); uncatalogued: 1, 227.5 mm standard length, Fars, Mand River outside Jahrom (28º36'N, 53º37'E); 1, 219.0 mm standard length, Khuzestan, Rud Zard, (31º22'N, 49º43'E); 3, 105.0- ca. 420.0 mm standard length, Khuzestan (no other locality data).

Comparative material:- BM(NH) 1875.1.14:7, 2, 341.8-569.1 mm standard length, Iraq, Baghdad (33º21'N, 44º25'E); BM(NH) 1912.5.2:8, 1, 314.3 mm standard length, Iraq, Shatt-al-Arab (no further locality data); BM(NH) 1920.3.3:297-300, 4, 134.5-289.6 mm standard length, Iraq, Basra (30º30'N, 47º47'E); BM(NH) 1920.3.5:7, 1, 103.8 mm standard length, Iraq, Basra (30º30'N, 47º47'E); BM(NH) 1922.3.25:1, 1, 424.0 mm standard length, Iraq, Baghdad (33º21'N, 44º25'E); BM(NH) 1936.3.10:4, 1, 40.0 mm standard length, Iraq, Nasiriyah (31º02'N, 46º16'E); BM(NH) 1974.2.22:1798, 1, 380.5 mm standard length, Iraq, Basra (30º30'N, 47º47'E); BM(NH) 1974.2.22:1807-1808, 2, 132.5-414.7 mm standard length, Iraq, Mosul (36º20'N, 43º08'E); BM(NH) 1968.12.13:440-442, 3, 178.9-351.2 mm standard length, Syria, Euphrates River at Mayadine (35º01'N, 40º27'E).