Taxonomy & naming
Polynemus multifilis was described by Temminck and Schlegel in 1843 from near Banjarmasin in southern Kalimantan, Indonesia. It is a threadfin in Polynemidae, named for the free filaments of the pectoral fin. FishBase lists the name Elegant paradise fish, and notes the Kapuas River population is replaced by Polynemus kapuasensis.
Morphology
FishBase gives a maximum length of 11 in SL. Threadfins have a subterminal mouth and pectoral fins split into several separate thread-like rays below the main fin.
Habitat
FishBase places it in the middle and lower sections of larger rivers and in estuaries, over sandy or muddy bottoms. It is recorded from Thailand and Indonesia, in fresh and brackish water.
Feeding
It feeds on crustaceans, small fishes and benthic organisms, according to FishBase.
Mating
Courtship has not been described in the sources used by the atlas.
Breeding
Breeding is not described in the sources used by the atlas.
In the aquarium
Polynemus multifilis is a large, active river fish that needs a long tank with a sandy bottom and strong filtration. FishBase notes it is exported to Japan as an ornamental. Feed meaty foods and keep it with fish too big to eat. FishBase gives no water chemistry for the species.
Conservation
The IUCN Red List lists Polynemus multifilis as Data Deficient, assessed 12 June 2018. FishBase notes it is a food fish, valued along the Chao Phraya River.