Delicate Blue Eye, Pseudomugil tenellus Taylor 1964

Other Names: Arnhem Land Blue-eye, Delicate Blue-eye

Delicate Blue Eyes, Pseudomugil tenellus, from Fish River Station, Douglas Daly Research Farm, Northern Territory. Source: Dave Wilson via Robert Whyte / Flickr. License: CC BY Attribution-Noncommercial-NoDerivatives

The Delicate Blue Eye is a small species patchily distributed in northern Australia. Males and females can be distinguished by differences in body colour and the larger size of the males fins. The mid-lateral row of scales appears as pearly spots.

Cite this page as:
Vanessa J. Thompson, Pseudomugil tenellus in Fishes of Australia, accessed 08 Dec 2023,

Delicate Blue Eye, Pseudomugil tenellus Taylor 1964

More Info


Found in the Northern Territory and Queensland, from the Finniss River to East Alligator River system, NT, and the Edward River area of Cape York Peninsula, QLD. Also occurs in south-western Papua New Guinea. 
Inhabits freshwater billabongs, quiet backwaters and overflow pools of rivers and creeks. Usually found in areas with muddy and gravel bottoms and abundant aquatic vegetation including water lilies.


Dorsal fin III-V + 6-7; Anal fin 7-10; Pectoral fin 10-12. 
Body relatively elongate, laterally compressed; greatest body depth 21.2-24.8% SL; head length 27.4-29.1 in SL; snout length 5.0-7.4 in SL; jaws strongly inclined; mouth small, superior with a protractile maxillary; jaw teeth conical to caniniform, premaxillary teeth not exposed when mouth closed; vomer and palatines toothless; eye large, diameter 8.7-10.3.

Scales cycloid with well-developed radii; horizontal scale rows 8; vertical scale rows 25 to 28; cheek scales 3-4;

Two separate dorsal fins; first dorsal fin origin just behind tips of pectoral and anterior to anal fin origin; anal fin origin in front of second dorsal origin; base of second dorsal and anal fins short. dorsal and anal fins lack rigid spines; pectoral fins short and set in a horizontal plane; fin rays not elongate in males.


To 5.5 cm SL, commonly to 4 cm or less.


Semi-transparent to light blue-grey; golden yellowish above midlateral stripe; network of dark scale margins dorsally; midlateral stripe consisting of series of discontinuous silvery spots becoming larger in older fish; basal areas of second dorsal and anal fins dark, with outer margins light yellow.


Feeds mostly on micro-crustaceans, insect larvae and algae.


Breeds mostly during the early wet season. Males display to females by intensifying their colours and erecting their ornate fins. Breeding episodes last several days with females depositing 4-10 adhesive eggs per day amongst aquatic vegetation. Larvae hatch in 2-3 weeks.


A popular aquarium fish.


Not listed


Colour varies with geographic location, reproductive condition and water conditions.

Similar Species

Pseudomugil tenellus differs from others in the genus in anal fin ray and transverse scale counts.


Pseudomugil is from the Greek pseudes meaning 'false' and the Latin mugil meaning 'a fish'. The specific name tenellus is from the Latin meaning 'delicate'.

Species Citation

Pseudomugil tenellus Taylor, W.R. (1964). Fishes of Arnhem Land. Rec. Am.-Aust. Sci. Exp. Arnhem Land 4: 44–307 figs 1–68 [132]. Arnhem Land, NT.


Vanessa J. Thompson

Delicate Blue Eye, Pseudomugil tenellus Taylor 1964


Allen, G.R. 1989. Freshwater Fishes of Australia. Neptune, New Jersey : T.F.H. Publications 240 pp., 63 pls.

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. & Cross, N.J. 1982. Rainbowfishes of Australia and Papua-New Guinea. New Jersey : T.F.H. Publications 142 pp. figs.

Bishop, K.A., S.A. Allen, D.A. Pollard & M.G. Cook. 2001. Ecological studies on the freshwater fishes of the Alligator Rivers Region, Northern Territory. Autecology. Supervising Scientist Report 145, Supervising Scientist, Darwin.

Larson, H.K. & Martin, K.C. 1990. Freshwater Fishes of the Northern Territory. Northern Territory Museum of Arts and Sciences Handbook Series Number 1. Darwin : Northern Territory Museum of Arts and Sciences 102 pp. 73 figs.

Leggett, R. & Merrick, J.R. 1987. Australian Native Fishes for Aquariums. Artarmon : J.R. Merrick Publications 241 pp. 142 figs.

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

Saeed, B., Ivantsoff, W. & Allen, G.R. 1989. Taxonomic revision of the family Pseudomugilidae (Order Atheriniformes). Australian Journal of Marine and Freshwater Research 40: 719-787

Semple, G.P. 1985. Pseudomugil tenellus - maintenance, reproduction and early development of the delicate blue-eye. Fishes of Sahul 3(2): 109-113.

Taylor, W.R. 1964. Fishes of Arnhem Land. Records of the American-Australian Scientific Expedition to Arnhem Land 4: 44-307 figs 1-68

Quick Facts

CAAB Code:37245021

Habitat:Quiet freshwaters

Max Size:5.5 cm


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CAAB distribution map