Polydactylus macrophthalmus (Bleeker, 1858)
River threadfin
photo by FAO

 Family:  Polynemidae (Threadfins)
 Max. size:  52 cm TL (male/unsexed)
 Environment:  demersal
 Distribution:  Asia: Kapuas River, Kalimantan and the Musi and Batanghari rivers, Sumatra, Indonesia.
 Diagnosis:  Dorsal spines (total): 9-9; Dorsal soft rays (total): 13-14; Anal spines: 3-3; Anal soft rays: 11-11. Occipital profile concave in adults. Pectoral filaments 7 with 3 filaments extending beyond caudal fin base and the fifth extending beyond tip of caudal fin lobe. Long pectoral fin rays, 24-26% of SL (Ref. 40968, 41110).
 Biology:  Known only from three rivers on two Indonesian islands: Kapuas River, Kalimantan and Musi and Batanghari rivers, Sumatra. These rivers were part of one large river, the ancient Central or North Sunda River, on the Sundaland during the Pleistocene, the last cold period about 12,000 years ago. Geographic evidence indicates that the species was well adapted to the freshwater basins in this extensive Pleistocene river, whereas other Polydactylus species are generally marine. With Sundaland submerged to about 100 m, this species is now restricted to the 3 presently known localities. The longer pectoral filaments and a more slender body have been considered as an adaptation to its freshwater existence. The long pectoral filaments are useful as a sense organ to search for food in muddy waters (Ref. 40968). A food fish along the Kapuas River, Borneo (Ref. 9685).
 IUCN Red List Status: Not Evaluated  (Ref. 96402)
 Threat to humans:  harmless
 Country info:   

 Entered by: Capuli, Estelita Emily - 11.08.95
 Modified by: Garilao, Cristina V. - 29.08.06

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