Overview
Its color is generally silvery with a darker, blue grayish back. The pectoral fins are orangish; the dorsal fins and tail, slaty gray. Live fish may have a golden to pinkish flush over the silvery sides, and this is believed by some to have led to the misnomer, “salmon” In fact, the threadfins are in no way related to the salmons or to their relatives of the Salmonidae family. It has a deeply forked tail and two fairly large dorsal fins of approximately equal size. The tail lobes are long but do not end in extended filaments as they do in the Indian threadfin. The single anal fin is similar in size and shape to the second dorsal fin.
Taxonomy
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Perciformes
- Family
- Polynemidae
- Genus
- Polydactylus
- Species
- macrochir
Habitat
King threadfin primarily inhabit coastal marine waters, estuaries, and the lower reaches of rivers in the Indo-West Pacific region, including northern Australia and southern New Guinea. They prefer areas with soft substrates like mud or sand and can tolerate a wide range of salinities, from fully marine to brackish environments. This adaptability allows them to thrive in both shallow inshore areas and depths up to about 20 meters.
Diet
King threadfin mainly feed on small fish, crustaceans such as prawns and crabs, and occasionally mollusks or worms. They are opportunistic bottom-feeders that hunt individually or in schools, often becoming more active at night or during low light conditions. Feeding behavior involves probing the substrate for prey in estuarine and coastal waters.
Behavior
King threadfin are schooling fish that form loose groups in open waters and estuaries, making them more visible during migration or feeding. They are primarily nocturnal, with increased activity at dawn and dusk, and exhibit migratory behavior in response to seasonal changes in water temperature and salinity. They can be territorial around spawning sites but generally tolerate crowded conditions in their habitats.
Fishing
Fishing for threadfins is best when a run in or run out tide is underway, clouding and muddying up the waters, at the mouths of estuaries and saltwater creeks. It seems to prefer foraging for its food (crabs, prawns, and the like) under the cover of a top layer of sediment. Live baits fished at night have also been known to catch large specimens, as have poppers and plugs at dusk. It is a “lazy” swimmer like the bonefish when foraging, but might be described as a tornado on a string once hooked, seemingly going in all directions at once. It may also leap from the water or streak off on long runs. It is frequently compared with the barramundi for its eating quality
Conservation Status
Listed as Not Evaluated by IUCN.