Pacific Blue Eye, Pseudomugil signifer Kner 1867

Other Names: Blue Eye, Blue-eye, Island Blue-eye, Northern Blue Eye, Northern Blue-eye, Pacific Blue-eye, Southern Blue-eye

A Pacific Blue Eye, Pseudomugil signifer, in Colosseum Creek, Queensland, October 2008. Source: leo-seq / License: CC BY Attribution-NonCommercial

The Pacific Blue Eye is a relatively large, common species that displays a wide range of morphological variation among geographic areas. This species is found along the Queensland and New South Wales coast and tolerates a wide range of salinities from fresh water to sea water. A distinctive long-finned variety occurs in coastal north Queensland.
Pacific Blue Eyes in Babinda Creek, Wanyurr Majay Yidinji Country, Far North Queensland.

Cite this page as:
Thompson, V.J. & Bray, D.J. 2022, Pseudomugil signifer in Fishes of Australia, accessed 20 Jun 2024,

Pacific Blue Eye, Pseudomugil signifer Kner 1867

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Widespread in streams and estuaries along eastern Australia, usually within 15-20km of the sea - from Weipa in the Gulf of Carpentaria and the Torres Strait Islands, Queensland, to the Wonboyn River Estuary, southern New South Wales, including some offshore islands such as Lizard Island, the Low Isles and Fraser Island, Queensland. 
Occurs in a range of marine to freshwater habitats, including tidal mangrove creeks and fringing coastal mangroves, coastal lakes, around offshore islands, and clear, cool, fast-flowing forest streams. Forms loose schools of hundreds to thousands of individuals.


Dorsal fin III-VI + 7-11; Anal fin 10-13; Pectoral fin 9-14; Pelvic fin 5; Caudal fin 15

Body relatively elongate, laterally compressed; greatest body depth 23.3-30.4 in SL; head length 26.3-28.4 in SL; snout length 6.1-8.0 in SL; mouth subvertical and small with a protractile maxillary; jaw teeth conical to caniniform, posterior premaixillary teeth enlarged and exposed when mouth closed; with or without one or more rows extending outside of mouth; vomer and palatines toothless; eye relatively large, eye diameter 9.0-10.5 in SL; mandibular pores present; head pores large.

Scales relatively large, cycloid with well-developed radii; horizontal scale rows 6; vertical scale rows 26 to 30; cheek with few scales.

Two separate dorsal fins; dorsal and anal fins lack rigid spines; first dorsal originating before tip of pectoral about midway along body; anal originating under end or just behind first dorsal and in front of second dorsal origin; pectoral fins pointed, short and set in a horizontal plane; males with elongate anterior dorsal, anal and ventral fin rays; caudal fin forked with rounded tips.


To 7cm SL, commonly to 4 cm.


Eye blue; body and fin coloration varies from semi-transparent yellowish-tan to silvery blue-grey with dark scale outlines; often with a row of long white spots across mid-line; iridescent mid lateral spots often present; fins clear to yellow-orange; males with black blotches at base of anal and second dorsal fins which may also have a white edge; males color intensifies during breeding.


Feeds mainly on micro-crustaceans and insect larvae.


Breed opportunistically throughout the year. 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. 
Eggs have adhesive filaments and are around 1.8mm in diameter. Larvae hatch in 2-3 weeks at 22ºC to 24ºC. Larvae are well developed at hatching and are capable of feeding immediately. Often observed in aggregations of tens to hundreds of individuals.


A popular aquarium fish, and bred in captivity.


IUCN: Least Concern


Pseudomugil signifier exhibits a wide range of morphological forms with at least 15 geographical varieties recognised. The fins of males and females also differ in shape and colour, particularly during breeding. The dorsal, anal and pelvic fins of males only are extended into filaments and become more intensely coloured during breeding.

Similar Species

Differs from the similar Honey Blue Eye, Pseudomugil mellis, in having larger scales on the nape, larger cephalic sensory pores, and the dorsal, anal and caudal fins of males are generally yellow with a black edge (vs. black banded fins with a white edge in P. mellis).


The specific name signifier is from the Latin signum (= flag) in reference to the elongate dorsal and anal fins of males.

Species Citation

Pseudomugil signifer Kner 1867, Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch-Naturwissenschaftliche Classe 53: 543. Type locality: Sydney, New South Wales.


Thompson, V.J. & Bray, D.J. 2022


Atlas of Living Australia

Pacific Blue Eye, Pseudomugil signifer Kner 1867


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Quick Facts

CAAB Code:37245020

Conservation:IUCN Least Concern

Fishing:Aquarium fish

Habitat:Freshwater to marine

Max Size:7 cm SL


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CAAB distribution map