Gertrude's Blue Eye (Pseudomugil gertrudae)

Family: Pseudomugilidae

Gertrude's Blue Eye — a Pseudomugilidae from Oceania, peaceful but energetic; needs open swimming room. Reaches 4–8 cm; shoaling; 8+ in a long tank unlocks full colour. 20–26 °C.

Care parameters

Water temperature: 20–26 °C
pH: 6.5–7.5
GH hardness: 5–15 dGH
Adult length: 4–8 cm
Minimum tank: 77 L
Water layer: Middle of the water column
Difficulty: Moderate
Temperament: Peaceful but energetic; needs open swimming room
Origin: Oceania

Species overview

A Pseudomugilidae species native to Oceania: Pseudomugil gertrudae lives middle of the water column over warm freshwater streams and lakes. Peaceful but energetic; needs open swimming room. Adults reach 4–8 cm. It is one of the aquarium-kept Pseudomugil species we profile, alongside Pseudomugil furcatus.

Native biotope

Habitat: Warm freshwater streams and lakes
Flow: Still to gentle current
Dissolved O₂: Moderate oxygen levels

Aquascape & hardware

Substrate: Fine sand and gravel
Hardscape: Driftwood and smooth stones
Plants: Hardy common aquarium plants

Temperament, diet & tankmates

Schooling: Shoaling; 8+ in a long tank unlocks full colour
Diet: Eager eater; varied diet maintains iridescence
Recommended tankmates: Robust peaceful cyprinids — Add motion without menace
Avoid keeping with: Small timid fish — Outcompeted at feeding time

Breeding & notes

Sexual dimorphism: Subtle external differences
Breeding method: Spawns among plants at dawn; no parental care

Frequently asked questions

Is Gertrude's Blue Eye easy to keep?

Intermediate difficulty. Peaceful but energetic; needs open swimming room; shoaling; 8+ in a long tank unlocks full colour.

What temperature and water chemistry does Gertrude's Blue Eye need?

Set the heater to 20–26 °C and avoid swings. pH 6.5–7.5, GH 5–15 dGH suit it.

How big does Gertrude's Blue Eye get, and what tank size?

Full size is 4–8 cm. Minimum tank: 77 L, with open swimming space along its middle of the water column habits.

What does Gertrude's Blue Eye eat?

Eager eater; varied diet maintains iridescence. Vary the menu — quality flakes or pellets plus frozen or live foods.

Can Gertrude's Blue Eye live with other fish?

Peaceful but energetic; needs open swimming room. Recommended tankmates: Robust peaceful cyprinids — Add motion without menace. Avoid Small timid fish — Outcompeted at feeding time.

Where does Gertrude's Blue Eye come from?

Native to Oceania, where it lives in warm freshwater streams and lakes. Still to gentle current; Moderate oxygen levels.

Does Gertrude's Blue Eye jump?

Low escape risk, but a lid is cheap insurance.

How does Gertrude's Blue Eye breed?

In the aquarium: spawns among plants at dawn; no parental care. Subtle external differences.