Pacific Blue-eye

The Pacific Blue-eye (Pseudomugil signifer) is a small fish in the family Pseudomugilidae, the blue-eyes, native to coastal drainages of eastern Australia from Queensland to New South Wales. Despite superficial similarities and a shared order with rainbowfish, blue-eyes form a distinct family known for their diminutive size and striking eye coloration. The species is one of the most widespread and commonly encountered blue-eyes in eastern Australia, occurring in a variety of coastal freshwater and brackish habitats. It is not considered threatened and remains abundant across much of its native range, frequently observed in shallow, still to slow-moving waters near river mouths and coastal wetlands.

Pacific Blue-eyes are very small fish, typically only 3-4 cm long.

• Body: slender, semi-translucent, silvery overall
• Eyes: bright, reflective blue iris, the species' most distinctive feature
• Fins: two small, separate dorsal fins; males show yellowish fins edged in black, especially the first dorsal and anal fins
• Tail: forked
• Size: notably smaller than most true rainbowfish, which helps distinguish it at a glance Its combination of tiny size, luminous blue eyes, and yellow-and-black edged fins in males readily separates it from juvenile rainbowfish and other small native fish sharing its habitat.

Pacific Blue-eyes occupy coastal streams, creeks, lagoons, and estuaries along the eastern Australian coastline, tolerating both freshwater and brackish conditions where rivers meet the sea. They favor still to gently flowing water with abundant vegetation, submerged structure, or overhanging cover, often in shallow margins rather than open channels. Their tolerance of fluctuating salinity allows them to move between fully fresh upstream reaches and more saline estuarine sections depending on season and rainfall. This adaptability makes them one of the more ecologically flexible small native fish along Australia's east coast.

Pacific Blue-eyes are highly social, schooling fish that move in tight, active groups near the surface and along vegetated margins. They feed primarily on zooplankton and small aquatic and aerial invertebrates, picking prey from the water column and surface film throughout the day. Breeding occurs over extended warmer periods, with males performing fin displays to attract females; eggs are laid among fine aquatic plants and hatch without further parental care. As small, abundant schooling fish, Pacific Blue-eyes are an important food source for larger native fish, wading birds, and other predators within coastal wetland and estuarine food webs.