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Pacific Blue-eye

Pseudomugil signifer

The Pacific blue-eye is an active, brightly colored schooling fish from Australia. Males display striking fins. Requires an 80L tank with dense plants, clean water, and a diet of small live or frozen foods.

Taxonomy
Class:Actinopteri
Order:Atheriniformes
Family:Pseudomugilidae
Genus:Pseudomugil
Species:Pseudomugil signifer

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Water Temperature

15 - 28 °C

pH Value

6.5 - 8

Water type

Freshwater / Brackish / Marine

Tank level

Surface and middle

Adult size

5 cm

Minimum tank volume

>= 60 L

Minimum group

>= 6

GH

5 - 15 dGH

KH

2 - 7 dKH

TDS

95 - 295 ppm

Conductivity

148 - 461 uS/cm

Species description

Geographical Origin and Habitat: Native to the coastal regions of eastern Australia, ranging from northern Queensland to southern New South Wales. It occupies diverse habitats, including slow-flowing forest streams, brackish estuaries, mangrove swamps, and tidal pools.
Taxonomy and Morphology: Belongs to the family Pseudomugilidae. A small fish reaching a maximum adult size of about 5 to 6 centimeters. Features two separate dorsal fins, a semi-translucent body, and striking electric blue eyes.
Social Behavior: Peaceful, active, and schooling. Must be kept in a group of 8 to 10 individuals or more; males perform stunning display dances during courtship, raising and lowering their large dorsal and anal fins to compete for female attention.
Coloration and Sexual Dimorphism: Body is semi-translucent yellow with metallic sheen. Adult males are larger and possess significantly larger, more ornate fins with black, white, and yellow tips and filaments. Females are smaller with clear, plain fins.

Care, breeding and tankmates

Aquarium Setup: An aquarium of 60-80 liters is recommended. Provide dense vegetation (such as Java moss and floating plants) along the back and sides, leaving a central open lane for swimming. Moderate water movement is highly beneficial.
Diet and Feeding: Omnivorous micro-predator. Readily accepts high-quality crushed flakes and micropellets; however, their diet must be supplemented with live or frozen foods such as baby brine shrimp, daphnia, cyclops, and microworms.
Water Quality: Highly adaptable, tolerating both freshwater and brackish conditions. Prefers a pH of 6.5-7.8, hardness of 5-15 dGH, and a temperature of 20-26 °C. Regular weekly water changes are crucial to prevent toxic buildup.
Compatibility and Cohabitation: Excellent fit for peaceful community tanks. Suitable tankmates include other blue-eyes, rainbowfish, small tetras, rasboras, corydoras, and freshwater shrimp; do not house with large or aggressive tankmates.
Aquarium Breeding: Egg scatterer. Adhesive eggs are laid daily in small batches on fine-leaved plants or spawning mops. Because parents may consume the eggs, it is best to transfer the plants or mops to a separate nursery tank for hatching.
Risks and Diseases: Sensitive to sudden shifts in water parameters and organic wastes. Prone to fungal infections and fin rot if water quality deteriorates, particularly affecting the delicate extended fins of mature males.

Geographic Origin and Distribution

Native to the coastal regions of eastern Australia, ranging from northern Queensland to southern New South Wales. It occupies diverse habitats, including slow-flowing forest streams, brackish estuaries, mangrove swamps, and tidal pools.

Origin

Australia, New Guinea, and Oceania

Fish profile

Temperament
Peaceful
The overall temperament of Pseudomugil signifer can be described as peaceful. Understanding their personality is vital for maintaining a peaceful and stress-free environment. They may exhibit unique behaviors when interacting with their surroundings or during feeding time. Careful consideration of their disposition leads to a more rewarding fishkeeping experience.
Diet
Omnivore
The natural diet of Pseudomugil signifer is primarily omnivorous. In captivity, they should be offered a varied selection of high-quality foods to meet their nutritional needs. Incorporating both dry commercial diets and frozen or live options will ensure optimal health and coloration. A varied diet prevents nutritional deficiencies.
Sex ratio
Harem
The ideal sex ratio for keeping Pseudomugil signifer is typically harem. Keeping them in these numbers helps reduce intraspecific aggression and mimics their natural social structure. Providing ample hiding spots can further alleviate tension among dominant individuals. Always monitor the group dynamics when introducing new specimens.
Feeding frequency
Twice daily
Feeding Pseudomugil signifer should generally be done twice a day. It is important to provide only what they can consume in a few minutes to prevent leftover food from decaying. Establishing a regular feeding schedule helps keep the fish active and healthy. Adjust the frequency if you observe signs of undernourishment or overfeeding.
Bioload
The bioload produced by Pseudomugil signifer is generally considered low. This means that the filtration system must be adequately sized to handle their waste output. Regular water changes and tank maintenance are strongly recommended to keep the environment healthy. Failure to do so can result in poor water quality and stress the fish.
Flow
Strong
In their natural habitat, Pseudomugil signifer experiences water flow that is moderate to high. Replicating this in the aquarium is crucial for their well-being and natural behavior. Appropriate water movement aids in oxygenation and prevents dead spots in the tank. Utilizing adjustable powerheads can help achieve the perfect balance.
Jump risk
Yes
The risk of Pseudomugil signifer jumping out of the aquarium is rated as high. Therefore, a tight-fitting lid or a secure mesh cover is highly recommended. Many fish jump when startled by sudden movements or poor water conditions. Securing the top ensures that your fish remain safely inside the tank.
Reproduction
Oviparous
Regarding reproduction, Pseudomugil signifer is known to be a egg-scatterer. Breeding them in a home aquarium requires specific water parameters and a dedicated setup. Providing the correct spawning media and conditioning the adults with high-quality foods will increase success. Raising the fry can be challenging and requires specialized microscopic foods initially.
Compatibility & tankmates
Community
When it comes to compatibility, Pseudomugil signifer is characterized as peaceful. They should be housed with tank mates that share similar water requirements and temperament. Care must be taken not to include species that could easily become prey or outcompete them for food. Observation is key to ensuring a harmonious community.
Tank level
Top/Middle
In the aquarium, Pseudomugil signifer prefers to occupy the top-mid level. Designing the aquascape to cater to this preference ensures the fish feel secure and display their best colors. Ensure that there is adequate swimming space and appropriate decor in their preferred zone. This vertical distribution also allows for careful selection of tank mates that occupy other levels.

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level
2.9 ± 0.38 se
Phylogenetic uniqueness (PD50)
0.5
Bayesian Length-Weight
a = 0.01122, b = 3.04
VulnerabilityLow vulnerability (10 / 100)

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Last updated: 06/30/2026
Pacific Blue-eye (Pseudomugil signifer) Care Guide & Tank Setup | Atlarium