Systematic position
Phylum: Chordata
Class: Actinopterygii (Ray-finned fishes)
Order: Perciformes (Perches)
Family: Polynemidae (Threadfins)
Genus: Eleutheronema
Species: E. tetradactylum
Synonyms
Polynemus coecus Macleay, 1878
Polynemus teria Hamilton, 1822
Polynemus tetradactylus Shaw, 1804
Common/local names
English: Fourfinger threadfin
Bangladesh: Tailla (তাইল্ল্যা)
India: Guchhia and Sahal (West Bengal) and Rawas (Maharashtra and Gujarat) (Talwar and Jhingran, 1991).
Distributions: Bangladesh, Persian Gulf, India, Pakistan, Sri Lanka, through the East Indies, to China, the Philippines and north and western Australia (Talwar and Jhingran, 1991).
Conservation status: Not threatened in Bangladesh (IUCN Bangladesh, 2000).
Morphology: Elongate and slightly compressed body. Anal and pelvic fin orange and lower part of pectoral fins with 4 free filamentous rays (Huda et al., 2003). Pectoral fin origin well belongs midline of body, pectoral filamentous rays white (Huda et al., 2003). Dorsal forked and lobs are equal. Body color silvery-green above and yellowish-white on sides and belly (Talwar and Jhingran, 1991). 75-80 scales on lateral line (Rahman, 1989 and 2005).
Fin formula:
D. VIII / 1/15-16; P1. 4+16-17; P2. I/5; A. 2/15-17 (Rahman, 1989 and 2005)
D1 VII, D2 I 13-15; A II 15-17; P 17+iv; V I 5 (Talwar and Jhingran, 1991)
Maximum lengths: 33.5 cm (Rahman, 1989 and 2005) and 200 cm (Huda et al., 2003).
Habitats: Estuaries, Bay of Bengal and tidal rivers of Bangladesh (Rahman, 1989 and 2005). Inhibits sandy inshore areas and muddy estuaries (Talwar and Jhingran, 1991). Available in Sundarbans (Huda et al., 2003). Ascends higher up the rivers than any other polynemids (Talwar and Jhingran, 1991).
Breeding: Ascends the estuary for breeding when the salinity of the water start raising (Talwar and Jhingran, 1991).
Fishery information: Excellent food fish and good fishery in the Hooghly estuary (Talwar and Jhingran, 1991).
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REFERENCES
Hamilton F (1822) An account of the fishes found in the river Ganges and its branches. Edinburgh & London. An account of the fishes found in the river Ganges and its branches.: i-vii + 1-405, Pls. 1-39.
Huda MS, Haque ME, Babul AS and Shil NC (ed.) (2003) Field guide to finfishes of Sundarban, Aquatic resources division, Sundarban, Boyra, Khulna, Bangladesh, p. 135.
IUCN Bangladesh (2000) Red book of threatened fishes of Bangladesh, IUCN- The world conservation union. xii+116 pp.
Macleay W (1878) The fishes of Port Darwin. Proceedings of the Linnean Society of New South Wales v. 2 (pt 4): 344-367, Pls. 7-9.
Rahman AKA (1989) Freshwater Fishes of Bangladesh, 1st edition, Zoological Society of Bangladesh, Department of Zoology, University of Dhaka, Dhaka-1000, pp. 269-270.
Rahman AKA (2005) Freshwater Fishes of Bangladesh, 2nd edition, Zoological Society of Bangladesh, Department of Zoology, University of Dhaka, Dhaka-1000, pp. 294-295.
Shaw G (1804) General zoology or systematic natural history … v. 5 (pt 1): i-v + 1-25, Pls. 93-132, 43+, 65+, 6+, 74+ and (pt 2): i-vi + 251-463, Pls. 132-182, 158+. General zoology or systematic natural history … Pisces.
Talwar PK and Jhingran AG (1991) Inland Fishes of India and Adjacent Countries, Vol. 2, Oxford & IBH Publishing Co. Pvt. Ltd. New Delhi-Calcutta, pp. 907-908.
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