An energetic and highly adaptable blue-eye species native to Eastern Australia. They inhabit a massive range of environments from rainforest streams to full-marine mangrove estuaries. Known for their striking blue eyes and the male's butterfly-like fin displays. They must be kept in schools, where males will constantly spar and flash their colors.
Pacific Blue Eye At a Glance
Pacific Blue Eye Tank Requirements
Will Pacific Blue Eye fit in your tank?
Care guides tell you what Pacific Blue Eye needs, the next question is whether your tank can safely provide it. Test Pacific Blue Eye against your tank size, maintenance needs, and the fish you already keep before you buy.
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Pacific Blue Eye Water Parameters
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Pacific Blue Eye Temperament & Compatibility
Pacific Blue Eye Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Males feature dramatically extended dorsal and anal fins, colored brilliantly in yellow/orange, which they flare to attract females and spar with rival males. Multiple males should be kept in a large school to disperse this harmless display aggression.
Differs in 2 traits from base species
Also known as: Show Male
Female
Females have much shorter, transparent fins and a slightly plumper body. They are entirely peaceful and should ideally outnumber males in the aquarium to prevent constant mating harassment.
Differs in 2 traits from base species
Pacific Blue Eye Care Guide Summary
The Pacific Blue Eye, scientifically known as Pseudomugil signifer, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 5 cm and have a fusiform body shape with a moderate growth rate. Classified as peaceful, this species primarily occupies the surface and mid-level zones of the aquarium and produces a low level of biological waste.
To thrive, the Pacific Blue Eye requires a brackish tolerant aquarium with a minimum volume of 60 litres and a tank length of at least 60 cm. Water temperature should be maintained between 20°C and 26°C, with a pH range of 6.5–8 and a general hardness of 5–15 dGH. A moderate water flow is preferred.
The Pacific Blue Eye is a rewarding species to keep, provided its core environmental needs are met. This species is available in 2 varieties: Male and Female. Each may differ slightly in size, temperament, or care needs, so it is worth checking the specific requirements of the variety you plan to keep.
Pacific Blue Eye Habitat Setup
When setting up an aquarium for the Pacific Blue Eye, a moderate water flow best suits their natural preferences. Because this species occupies the surface and mid-level zones, the aquarium layout should prioritise adequate surface area with floating cover to make them feel secure near the waterline and open swimming space in the centre of the tank for free movement. Useful additions include dense planting to provide cover, break sightlines, and reduce stress. Keepers should note that a tight-fitting lid is essential, as this species is a known jumper.
Pacific Blue Eye Compatibility Notes
Classified as peaceful, the Pacific Blue Eye is a schooling species that feels most secure in a sizeable group, where natural shoaling behaviour reduces stress and brings out their best colours. When choosing tankmates, their energetic swimming style may stress more sedentary or timid species. Selecting tankmates that favour different water layers from the surface and mid-level zones can help reduce competition and territorial overlap.
Pacific Blue Eye Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Pacific Blue Eye.
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
40 Gallon Breeder
Show 19 more tank sizes
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Frequently Asked Questions About Pacific Blue Eye
How big does Pacific Blue Eye get?
Pacific Blue Eye (Pseudomugil signifer) typically reaches a maximum adult size of approximately 5 cm. They have a fusiform body shape and a moderate growth rate.
What tank size does Pacific Blue Eye need?
A minimum aquarium volume of 60 litres and a tank length of at least 60 cm are recommended for Pacific Blue Eye. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Pacific Blue Eye need?
Pacific Blue Eye thrives in brackish tolerant conditions with a temperature range of 20–26°C, a pH between 6.5 and 8, and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Is Pacific Blue Eye peaceful or aggressive?
Pacific Blue Eye is classified as peaceful with an aggression score of 2 out of 10. They are generally well-suited to peaceful community tanks.
How many Pacific Blue Eye should be kept together?
Pacific Blue Eye is a schooling species and should be kept in groups of at least 6. Larger groups help distribute aggression and encourage natural schooling behaviour.
Does Pacific Blue Eye have any special tank requirements?
Yes. Pacific Blue Eye benefits from plants - densely covered in the aquarium. These features help replicate their natural habitat and promote overall health and well-being.
Does Pacific Blue Eye need a lid on the tank?
Yes. Pacific Blue Eye is a known jumper, and a tight-fitting lid or cover is essential to prevent escape. Even a small gap can be enough for a determined fish to leap out.
Top Tank Mates for Pacific Blue Eye
These fish are strong compatibility matches for Pacific Blue Eye based on water preferences, temperament, adult size, and tank behavior.
Hillstream Loach
Beaufortia leveretti
Ideal Tank MatesSchwartz's Cory
Corydoras schwartzi
Ideal Tank MatesLeopard Cory
Corydoras leopardus
Ideal Tank MatesHi Fin Peppered Cory
Scleromystax macropterus
Ideal Tank MatesGold Laser Cory
Corydoras sp. 'CW010'
Ideal Tank MatesDainty Cory (Salt and Pepper Cory)
Corydoras habrosus
Ideal Tank MatesPlants That Suit Pacific Blue Eye
These plants pair well with Pacific Blue Eye based on shared water preferences, layout fit, and how likely they are to hold up in the same aquarium.
Afzel's Anubias
Anubias afzelii
Amazon Sword
Echinodorus amazonicus
Anacharis
Egeria densa
Anubias Barteri
Anubias barteri
Baby Tears
Lindernia rotundifolia
Balansae
Cryptocoryne crispatula
Fish Similar to Pacific Blue Eye
Gertrude's Spotted Blue-eye
Pseudomugil gertrudae
A stunning, highly active nano fish native to Australia and New Guinea. Known for their striking blue eyes and the males' spectacular, heavily spotted fins which they flare during dominance displays. They are peaceful but require being kept in shoals to thrive and exhibit natural behaviors.
Kiunga Blue Eye
Kiunga ballochi
A tiny, critically rare micro-predator native to a very restricted area in the Upper Fly River system of Papua New Guinea. Characterized by a transparent 'glass' body with striking yellow and black fin margins. They are peaceful shoaling fish that require highly stable water conditions and a planted aquarium. Listed as Endangered on the IUCN Red List, they are a true rarity in the aquarium trade.
Blue Back Blue Eye
Pseudomugil cyanodorsalis
A tiny, highly active euryhaline species native to the mangrove swamps and tidal estuaries of Northern Australia. While biologically capable of surviving in pure freshwater or full marine conditions, they require a brackish aquarium (SG 1.005-1.015) to thrive, breed, and resist disease long-term. They are peaceful shoaling fish but spectacular jumpers, so a tight-fitting lid is absolutely mandatory.
Forktail Blue-eye
Pseudomugil furcatus
A highly active, nano shoaling fish native to Papua New Guinea. Recognized by their striking blue eyes and energetic swimming patterns. They are peaceful but require open horizontal swimming space and the company of their own kind to thrive. Due to their short lifespan (2-3 years), they mature quickly and display near-constant courtship behavior.
Honey Blue Eye
Pseudomugil mellis
A rare, stunning nano shoaling fish endemic to the acidic, tannin-stained 'wallum' heathlands of Queensland, Australia. Known for their honey-golden bodies and striking blue eyes, they are highly active but peaceful. They require mature, slightly acidic, soft water aquariums with dense planting. Listed as Endangered in the wild.
Delicate Blue-Eye
Pseudomugil tenellus
The Delicate Blue-Eye is a small, highly active shoaling fish native to the swamps and coastal floodplains of Northern Australia and New Guinea. They are euryhaline (tolerating both fresh and brackish water) and thrive in warm, densely planted aquariums. They are peaceful but require a group to feel secure and display their best behaviors.