Threadfin Rainbowfish, Iriatherina werneri Meinken 1974

Other Names: Featherfin Rainbowfish, Threadfin Rainbow Fish

Threadfin Rainbowfish, Iriatherina werneri, Gulbuwangay River, Northern Territory. Source: Dave Wilson / Aquagreen. License: All rights reserved

Males of this very small slender rainbowfish are easily recognised by their large rounded first dorsal fin, and the long dark rays extending from their pelvic, second dorsal and anal fins. 

Video of a male Threafin Rainbowfish displaying to a female.

Cite this page as:
Gomon, M.F. & Bray, D.J. 2017, Iriatherina werneri in Fishes of Australia, accessed 17 Jun 2024,

Threadfin Rainbowfish, Iriatherina werneri Meinken 1974

More Info


Goyder, NT and Jardine River system near the N extremity of Cape York Peninsula, QLD. Inhabits slow-flowing streams, swampy ponds and billabongs with abundant aquatic vegetation and temperatures between 23°C-28°C.


Dorsal fin VI-IX +  I, 7; Anal fin I,10-12; Pectoral fin 9-12.
Body relatively elongate, laterally compressed; greatest body depth 4.6 to 5.6 in standard length; lateral line absent; jaw teeth conical to caniniform, one or more rows extending outside of mouth; vomer and palatines toothless; gill rakers on lower limb of first gill arch 11 to 13; vertebrae 32 or 33; head length 27.9-30.0 in SL; snout length 5.9-8.0 in SL; eye relatively large, diameter 10.7-12.4 in SL; sexual dimorphism characterized by extremely elongate rays at beginning of anal and second dorsal fins of males.
Scales relatively large, cycloid with well-developed radii, horizontal rows on body at level of anal fin origin usually 9 or 10, vertical rows from upper corner of gill opening to caudal fin base 30 or 31
Two separate dorsal fins, anal fin long-based; first dorsal fin consisting of 6 to 9 slender flexible spines; second dorsal fin with a stiff spine and 7 segmented rays; males with a large fan-shaped first dorsal fin and 2-3 long thread-like filaments on the anal and second dorsal fins; anal fin with a stiff spine and 10 or 12 segmented rays; anal fin originates on anterior half of body; only last 3 to 4 rays of second dorsal fin and last 3 to 8 rays of anal fin branched; upper and lower caudal fin margins elongate.


To 4 cm SL, commonly to 3 cm.


Generally brownish with silvery reflections, darker brown to olive-green or bluish above, especially in males. Elongated anal and second dorsal fin rays in males are black and upper and lower caudal margins and first dorsal are orange to red.


Feed on insects and their larvae, micro-crustaceans and algae.


Spawning occurs mostly yearound, and females deposit small numbers of eggs daily in weedy areas. Eggs are small with adhesive filaments. Hatching occurs after 7-10 days.

Species Citation

Iriatherina werneri Meinken, 1974, Aquarium (Berl.) 55(8): 3 pp. 3 figs. Type locality: near Merauke, Irian Jaya.


Gomon, M.F. & Bray, D.J. 2017

Threadfin Rainbowfish, Iriatherina werneri Meinken 1974


Allen, G.R. & Hoese, D.F. (1980). A collection of fishes from the Jardine River, Cape York Peninsula, Australia. J. R. Soc. West. Aust. 63(2): 53–61

Allen, G.R. & Cross, N.J. (1982). Rainbowfishes of Australia and Papua-New Guinea.  New Jersey : T.F.H. Publications 142 pp.

Allen, G.R. (1989). Freshwater Fishes of Australia.  Neptune, New Jersey : T.F.H. Publications pp. 1–240

Allen, G.R., Midgley, S.H. & Allen, M. (2002). Field guide to the freshwater fishes of Australia.  Perth : Western Australian Museum 394 pp.

Meinken, H. (1974). Aus Neu-Guinea kommt eine neue Gattung und Art der Ahrenfishe (Pisces, Antherinidae). Aquarium (Berl.) 55(8): 3 pp. 3 figs [pages not numbered].

Merrick, J.R. & Schmida, G.E. (1984). Australian Freshwater Fishes Biology and Management.  Sydney : J.R. Merrick 409 pp.

Leggett, R. & Merrick, J.R. (1987). Australian Native Fishes for Aquariums.  Artarmon : J.R. Merrick Publications 241 pp.

Quick Facts

CAAB Code:37245003

Fishing:Popular aquarium fish


Max Size:4 cm SL

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