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

A transparent to greyish glassfish with a network pattern of dark-edged scales, and the posterior end of the lateral line is well developed with tubed scales.

Cite this page as:
Thompson, V.J. & Bray, D.J. 2020, Ambassis elongatus in Fishes of Australia, accessed 06 May 2021,

Elongate Glassfish, Ambassis elongatus (Castelnau 1878)

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Endemic to the Gulf of Carpentaria Drainage from the southern Gulf to the tip of Cape York and Torres Strait islands, Far North Queensland. Inhabits freshwater creeks and rivers around the margin, schooling amongst vegetation. The species often occurs in freshwater streams that frequently have moderate to high turbidity levels.


Dorsal fin VII, I, 8; Anal fin III, 7-8; Pectoral fin 13-14; Gill rakers 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 large, cycloid, 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.


IUCN Red List: Least Concern


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 the Elongate Glassfish, 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 1878, Proc. Linn. Soc. N.S.W. (1)3(1): 44. Type locality: Norman River, Queensland.


Thompson, V.J. & Bray, D.J. 2020


Atlas of Living Australia

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. 

Allen, G.R. & Burgess, W.E. 1990. A review of the glass-fishes (Ambassidae) of Australia and New Guinea. Records of the Western Australian Museum, Supplement 34: 139-206 

Castelnau, F.L. de 1878. Notes on the fishes of the Norman River. Proceedings of the Linnean Society of New South Wales 1 3(1): 41-51 

Gill, A.C., Russell, B.C. & Nelson, G.J. 2018. F.L. de Castelnau’s Norman River fishes housed in the Macleay Museum, University of Sydney. Zootaxa 4459( 3): 565-574 https://doi.org/10.11646/zootaxa.4459.3.9

Grant, E.M. 2002. Guide to Fishes. Redcliffe : EM Grant Pty Ltd 880 pp. 

Hitchcock, G., Finn, M.A., Burrows, D.W., & Johnson, J.W. 2012. Fishes from fresh and brackish waters of islands in Torres Strait, far north Queensland. Memoirs of the Queensland Museum 56(1): 14-24 

Kennard, M. & Brooks, S. 2019. Ambassis elongatus. The IUCN Red List of Threatened Species 2019: e.T1075A123377611. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T1075A123377611.en. Downloaded on 09 September 2020.

Lake, J.S. 1978. Australian Freshwater Fishes. Melbourne : Thomas Nelson 160 pp. 140 figs.

Merrick, J.R. & Schmida, G.E. 1984. Australian Freshwater Fishes Biology and Management. Sydney : J.R. Merrick 409 pp. figs 280 col. figs. 

Pusey, B.J., Burrows, D.W., Kennard, M.J., Perna, C.N., Unmack, P.J., Allsop, Q. & Hammer, M P. 2017. Freshwater fishes of northern Australia. Zootaxa 4253(1): 1-104.

Unmack, P.J. 2001. Biogeography of Australian freshwater fishes. Journal of Biogeography 28: 1053-1089 

Whitley, G.P. 1935. Fishes from Princess Charlotte Bay, North Queensland. Records of the South Australian Museum (Adelaide) 5(3): 345-365 figs 1-11

Quick Facts

CAAB Code:37310010

Conservation:IUCN Least Concern

Habitat:Coastal freshwater streams

Max Size:5-5 cmSL


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Species Maps

CAAB distribution map