Eleutheronema tetradactylum (Shaw, 1804)
Fourfinger threadfin
photo by Randall, J.E.

Family:  Polynemidae (Threadfins)
Max. size:  200 cm TL (male/unsexed); max.weight: 145 kg
Environment:  pelagic-neritic; depth range 0 - 23 m, amphidromous
Distribution:  Indo-West Pacific: Persian Gulf to Papua New Guinea and northern Australia. Replaced by Eleutheronema rhadinum (Jordan & Evermann, 1902), in East Asia (Japan, China, Viet Nam).
Diagnosis:  Dorsal spines (total): 9-9; Dorsal soft rays (total): 13-15; Anal spines: 3-3; Anal soft rays: 14-16; Vertebrae: 25-25. This species is distinguished with the following characters: second dorsal fin soft rays 14 (rarely 13 or 15) pectoral fin rays 16-18 (mode 17, rarely 15 or 19), pectoral filaments 4; pored lateral line scales 71-80 (mode 73); scale rows above lateral line 9-12, below 13-15 (14); vomer with deciduous tooth plates on both sides, except in juveniles (< ca. 7.0 cm SL); posterior part of maxilla deep, 3-4% of SL; short tooth plate extension onto lateral surface of lower jaw, 7-9% SL. Colour of upper sides of head and trunk with slight darkish silver tinge, becoming lighter in lower sides; anterior margins of first and second dorsal fins blackish, remaining parts translucent and slightly blackish, respectively; pectoral fin membranes vivid yellow in life, except in large specimens > ca 35 cm SL which is dusky yellow; pectoral filaments white; anterior margin of pelvic fin yellow and other parts white; base of caudal fin yellowish, other parts blackish (Ref. 41639, 57343).
Biology:  Adults occur mainly over shallow muddy bottoms in coastal waters. Also enter rivers (Ref. 3479, 6390, 11230). Juveniles found in estuaries. During winter, adults ascend the rivers. They usually form loose schools, although larger fish are more often observed in pairs or singly (Ref. 6390). Feed on prawns and fish (largely members of Mugilidae, Engraulidae, and Sciaenidae) with occasional polychaetes. Frequency of crustaceans to fish in the diet varies seasonally. Larvae (7-30 mm TL) feed mainly on copepods and mysids but also take shrimps and prawn larvae (Ref. 57343). Juveniles (31-60 TL) feed on prawns shrimps and mysids (Ref. 57343). Protandrous hermaphrodites. Marketed fresh, frozen, and dried or salted.
IUCN Red List Status: Not Evaluated (N.E.) Ref. (120744)
Threat to humans:  harmless
Country info:   
 

Entered by: Luna, Susan M. - 17.10.90
Modified by: Luna, Susan M. - 18.11.13
Checked by: Luna, Susan M. - 07.04.99

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