Pacific Blue Eye

Pseudomugil signifer

Also known as: Pacific blue-eye, Blue-eye

Water Parameters

• Temperature: 16–28°C
• pH: 7–8
• Hardness (GH): 143–357 ppm (8–20 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

A native Australian rainbowfish relative from the coastal streams and estuaries of the eastern seaboard, and a quietly rewarding nano fish for keepers interested in local species. What it lacks in size it makes up in behaviour: a group of males constantly displays, fanning out their finnage and sparring without harm in a shimmer of pale blue and yellow, lit by the luminous blue eye that gives the fish its name. They are short-lived, rarely beyond a few years, and appreciate a stable, mature tank with fine live or frozen foods, which makes them a touch more demanding than their hardiness suggests. Their tolerance for hard, alkaline, even slightly brackish water suits much of coastal Australian tap supply and pairs them naturally with a native or hard-water biotope. An understated, characterful choice, and a nod to local fauna.

Tankmates

A tiny, peaceful, surface-oriented schooling fish, too small to threaten any tankmate and too small to be safe with most: anything large enough to eat a 3cm fish eventually will, so keep them only with other nano species and peaceful invertebrates. Genuinely shrimp-safe, even with shrimplets, thanks to a tiny mouth. Keep them in a group of at least eight, ideally a dozen or more, where the males spend the day flaring their fins and displaying to one another in harmless mock contests, which is the main reason to keep them. They suit the hard, alkaline coastal tap water common along eastern Australia, and tolerate the slightly brackish conditions of some of their native habitats. Best in a mature, planted, gently-filtered nano tank.

Compatible with

• Celestial Pearl Danio
• White Cloud Mountain Minnow
• Ember Tetra
• Cherry Shrimp
• Amano Shrimp
• Pygmy Corydoras
• Otocinclus
• Nerite Snail
• Gertrude's Blue Eye
• Threadfin Rainbowfish
• Murray River Rainbowfish
• Forktail Blue Eye

Avoid keeping with

• Betta
• Angelfish
• Large Cichlids
• Paradise Fish
• Any Larger Fish

Common Problems

• short lifespan (typically 2 to 3 years)
• predation by any larger tankmate
• reluctance to take dry food (prefers small live or frozen)
• stress and poor colour in groups smaller than 8

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20