POLYNEMIDAE Eleutheronema tetradactylum, 15.4 cm SL (photo by Seishi Kimura) Eleutheronema tetradactylum, 11.2 cm SL (photo by Seishi Kimura) Eleutheronema tetradactylum (Shaw, 1804) Fourfinger Threadfin D VIII+I, 13-15, 9; A III, 14-16; P1 15-19+4 filaments; P2 I, 5; LLp 71-80; GR 6-18. Body elongate, moderately compressed. Posterior margin of maxilla extending well beyond a vertical through posterior margin of adipose eyelid. Upper jaw length 5.9-7.1 in SL. Anterior parts of lower jaw with small teeth extending onto lateral surface, adjacent portion of lip absent; tooth plate extension onto lateral surface of lower jaw 11.1-14.3 in SL; vomer with deciduous tooth plates on both sides, except in juveniles. Longest pectoral filament not reaching origin of anal fin. Swimbladder absent. Color: upper sides of head and trunk with slight darkish silver tinge, becoming lighter on lower sides. Anterior margins of first and second dorsal fins blackish, remaining parts translucent and slightly blackish, respectively; pectoral fin vivid yellow (dusky yellow in large specimens over ca. 350 mm SL). Size: maximum length about 200 cm. Distribution: distributed in the Indo-West Pacific, from the Persian Gulf east to Papua New Guinea and northern Australia. Remarks: generally occurs on continental shelves on muddy and sandy substrata, and frequently enters brackish waters, especially as juveniles. Sex changing male to female with growth.