Gertrude's Blue Eye

Pseudomugil gertrudae

Also known as: Spotted blue eye, Gertrude's blue-eye, Spotted blue-eye

Water Parameters

• Temperature: 24–28°C
• pH: 5.5–7.5
• Hardness (GH): 36–143 ppm (2–8 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 second native Australian blue-eye to set beside the pacific blue eye, and an even smaller one: barely 3cm long, the spotted blue eye is patterned with fine dark spots over a pale, shimmering body, lit by the brilliant blue eye the group is named for, and the males spend the day flaring their spotted, yellow-tipped fins at one another in harmless contests. Native to the soft, tannin-stained streams and swamps of tropical northern Australia and New Guinea, it prefers warmer, softer water than its coastal cousin and shows beautifully in a planted, dimly-lit blackwater nano tank. It is short-lived, has a tiny mouth that needs small foods, and is best kept in a good-sized group, all of which place it just past absolute-beginner territory. A characterful, jewel-like showcase of Australia's native fauna.

Tankmates

A tiny, peaceful, surface-loving schooling fish and a natural companion for its larger relative the pacific blue eye, sharing the same gentle temperament and the same need for a group of at least eight to bring out the males' constant fin-flaring displays. Genuinely shrimp-safe thanks to a minute mouth, and far too small to threaten any tankmate, but equally vulnerable to being eaten, so it belongs strictly in a nano community of similarly tiny, peaceful species. Unlike the hard-water pacific blue eye, gertrude's blue eye comes from soft, often tannin-stained waters, so it suits a planted blackwater-style nano tank. A delightful, slightly delicate native for a dedicated small setup.

Compatible with

• Pacific Blue Eye
• Celestial Pearl Danio
• Ember Tetra
• Chili Rasbora
• Pygmy Corydoras
• Cherry Shrimp
• Otocinclus

Avoid keeping with

• Betta
• Angelfish
• Large Cichlids
• Fin Nippers
• Any Larger Fish

Common Problems

• short lifespan (typically 1 to 2 years)
• preference for small live or frozen foods
• predation by any larger tankmate
• stress and poor display in groups smaller than 8

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