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.
At a Glance
Tank Requirements
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Water Parameters
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Temperament & Compatibility
Available Varieties
Each variety inherits the species defaults above. Only differences are highlighted.
Male
Males feature extended, bright yellow dorsal and ventral fins, and a distinctively yellow-edged forked tail. They spend much of their time displaying to females and mock-sparring with other males without doing physical harm.
Differs in 1 trait from base species
Also known as: Display Male, Standard
Female
Females are slightly smaller, plumper in the belly, and have shorter, translucent or very pale yellow fins. Keeping a ratio of at least 1 male to 2 females reduces courtship stress on the females.
Differs in 2 traits from base species
Also known as: Unsexed, Juvenile
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🟢Ideal Tank MatesForktail Blue-eye Care Guide Summary
The Forktail Blue-eye, scientifically known as Pseudomugil furcatus, belongs to the Rainbowfish family group. Adults reach a maximum size of approximately 5 cm and have a fusiform body shape with a fast 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 Forktail Blue-eye requires a freshwater only aquarium with a minimum volume of 55 litres and a tank length of at least 60 cm. Water temperature should be maintained between 24°C and 28°C, with a pH range of 7–8 and a general hardness of 5–15 dGH. A moderate water flow is preferred. An aquarium test kit can help you monitor these values.
The Forktail 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.
Forktail Blue-eye Habitat Setup
When setting up an aquarium for the Forktail 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.
Forktail Blue-eye Compatibility Notes
Classified as peaceful, the Forktail 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.
Recommended Tank Sizes
Standard aquarium sizes that meet the minimum volume and length requirements for Forktail Blue-eye.
15 Gallon Standard
20 Gallon High
20 Gallon Long
29 Gallon Standard
30 Gallon Breeder
36 Gallon Bowfront
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Frequently Asked Questions About Forktail Blue-eye
How big does Forktail Blue-eye get?
Forktail Blue-eye (Pseudomugil furcatus) typically reaches a maximum adult size of approximately 5 cm. They have a fusiform body shape and a fast growth rate.
What tank size does Forktail Blue-eye need?
A minimum aquarium volume of 55 litres and a tank length of at least 60 cm are recommended for Forktail Blue-eye. This ensures enough swimming space and helps maintain stable water conditions.
What water parameters does Forktail Blue-eye need?
Forktail Blue-eye thrives in freshwater only conditions with a temperature range of 24–28°C, a pH between 7 and 8, and a general hardness of 5–15 dGH. A moderate water flow is preferred.
Is Forktail Blue-eye peaceful or aggressive?
Forktail 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 Forktail Blue-eye should be kept together?
Forktail 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 Forktail Blue-eye have any special tank requirements?
Yes. Forktail 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 Forktail Blue-eye need a lid on the tank?
Yes. Forktail 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.
Similar Species
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.
Threadfin Rainbowfish
Iriatherina werneri
A delicate and exquisitely shaped nano rainbowfish native to New Guinea and Northern Australia. They are famous for the males' long, filamentous fins and butterfly-like display behavior. Due to their incredibly small throats, they require micro-foods. They are shoaling fish that are easily intimidated by boisterous tank mates.
Turquoise Rainbowfish
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A stunning, deep-bodied rainbowfish endemic to Lake Kutubu in Papua New Guinea. Famous for their ability to shift colors from deep teal to bright iridescent blue depending on mood and water quality. They are active schooling fish that thrive in hard, alkaline water.
Panda Garra
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A highly active, beautifully patterned benthic (bottom-dwelling) fish native to the fast-flowing, highly oxygenated streams of Myanmar. They are excellent biofilm and algae grazers. While peaceful towards other species, they establish a strict, sometimes physical pecking order among themselves. They are notorious climbers and jumpers, requiring a tight-fitting lid.
Celebes Rainbowfish
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An active, schooling fish native to the karst (limestone) streams of Sulawesi, Indonesia. Known for their striking neon blue lateral stripes and yellowish fins. They strictly require hard, alkaline water to thrive and are highly sensitive to soft, acidic conditions. A peaceful species that requires plenty of open swimming space.
Red Rainbowfish
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Native to Lake Sentani in Indonesia, this species is famous for the brilliant salmon-red coloration of mature males. They are large, active schooling fish that develop a distinct high-arched back as they age. Females are vastly different in appearance (olive-gold). They require hard, alkaline water and plenty of swimming space.