Elongate Glassfish, Ambassis elongatus (Castelnau 1878)

Other Names: Yellow Fin Perchlet, Yellow-fin Perchlet

Elongate Glassfish, Ambassis elongatus. Source: Gerald R. Allen. License: all rights reserved

The Elongate Glassfish is a small perch-like species with a restricted distribution, known only from the Gulf of Carpentaria area of tropical Queensland. This species is transparent to grey in colour with a network pattern of dark-edged scales. The posterior end of the lateral line is well developed with tubed scales.

Cite this page as:
Vanessa J. Thompson, Ambassis elongatus in Fishes of Australia, accessed 07 Jul 2020,

Elongate Glassfish, Ambassis elongatus (Castelnau 1878)

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Known only from the O'Shannessy River (138º45´E), Leichardt River (139º49´E) and Norman River (141º08´E) in the Gulf of Carpentaria drainage, Queensland. Tropical,  inhabiting freshwater creeks and rivers around the margin amongst vegetation. Often in freshwater streams that frequently have moderate to high turbidity levels.


D VII, I, 8; A III, 7-8; P 13-14; GR on lower limb of 1st arch 17-18

Body laterally compressed, elongate-oval shaped; greatest body depth 33-38 % SL; head length 35.7 to 39.7 % SL; snout length 7.2 to 7.7 % SL; eye large, diameter 12.7 to 13.9 % SL; a single supraorbital spine; lateral line incomplete or in two sections, first dorsally to below spinous portion of dorsal usually with 10-14 tubed scales, second midlaterally on caudal peduncle with 0-11 pored scales; head with small spines; nasal spine absent.

Scales are cycloid and large, present on head; horizontal scale rows 11; vertical scale rows 25-26; cheek with 2 transverse scale rows.

Height of first dorsal fin 20.9 to 27.4 % SL; second dorsal spine slightly longer than third dorsal spine or spines about equal in length; third anal spine slightly longer than second anal spine.


To 5.5 cm


Semi-transparent to grey with dark scale edges forming a network pattern covering most of the body.


Likely to feed mainly on aquatic and terrestrial insects and micro-crustaceans.


Breeds in small ponds; likely to deposit small, adhesive eggs amongst aquatic vegetation.


Listed as lower risk/least concern on the IUCN Red List of Threatened Species.
Not listed under the Australian EPBC Act.


This species is common within its restricted distribution.

Similar Species

Similar to A. agrammus, but differs by having the anterior portion of the lateral line well developed, usually with 10 to 14 tubed scales and with 0 to 11 tubed scales in the posterior section. In addition, the preorbital ridge and adjoining suborbital series are smooth in elongatus and usually serrated in A. agrammus.


Ambassis comes from the Greek, ambasis, -ios, anabasis meaning climbing up. Species name elongatus from the Latin meaning prolonged/long. Common name Glassfish comes from the transparent appearance of this species.

Species Citation

Pseudoambassis elongatus Castelnau, F.L. de (1878). Notes on the fishes of the Norman River. Proc. Linn. Soc. N.S.W. (1)3(1): 41–51 [44]. Norman River, QLD.


Vanessa J. Thompson

Elongate Glassfish, Ambassis elongatus (Castelnau 1878)


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

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

Wager, R. 1996. Ambassis elongatus. In: IUCN 2010. IUCN Red List of Threatened Species. Version 2010.4. <www.iucnredlist.org>.

Whitley, G.P. (1935). Fishes from Princess Charlotte Bay, North Queensland. Rec. S. Aust. Mus. 5(3): 345–365

Quick Facts

CAAB Code:37310010

Habitat:coastal freshwater streams

Max Size:5.5 cm


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