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.
Forktail Blue-eye At a Glance
Forktail Blue-eye Tank Requirements
Will Forktail Blue-eye fit in your tank?
Care guides tell you what Forktail Blue-eye needs, the next question is whether your tank can safely provide it. Test Forktail Blue-eye against your tank size, maintenance needs, and the fish you already keep before you buy.
Forktail Blue-eye Water Parameters
Forktail Blue-eye Temperament & Compatibility
Forktail Blue-eye 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
Forktail 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.
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.
Who Forktail Blue-eye Is Actually For
Forktail Blue-eye is best for a fishkeeper who wants a species that can settle into a calmer community setup and can provide a keeper who can commit to a proper group of at least 6. It makes the most sense for a hobbyist who will actually build around its needs, especially plants.
The most common mistake is buying Forktail Blue-eye for looks first and only later discovering how its adult size, behavior, or bioload changes the whole tank plan. Another frequent problem is underestimating its social needs. A token pair or trio often behaves very differently from a real group.
Forktail Blue-eye 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
Show 20 more tank sizes
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.
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Guidarium Editorial Desk
Reviewed against Guidarium care, stocking, and compatibility standards. Read the editorial policy.
- Last reviewed
- April 28, 2026
- Last updated
- April 28, 2026
- Issues or corrections?
- Contact the editorial team
Top Tank Mates for Forktail Blue-eye
These fish are strong compatibility matches for Forktail Blue-eye based on water preferences, temperament, adult size, and tank behavior.
Trapdoor Snail
Cipangopaludina chinensis
Ideal Tank MatesSkunk Cory
Corydoras arcuatus
Ideal Tank MatesSan Juan Cory
Corydoras bilineatus
Ideal Tank MatesOrange Delight Shrimp
Caridina loehae
Ideal Tank MatesSchwartz's Cory
Corydoras schwartzi
Ideal Tank MatesLeopard Cory
Corydoras leopardus
Ideal Tank MatesPlants That Suit Forktail Blue-eye
These plants pair well with Forktail 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 Forktail 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.
Popondetta Blue-eye
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The Popondetta Blue-eye is a stunning, active nano fish native to the clear, fast-flowing streams of Papua New Guinea. Recognized by their bright blue eyes and striking finnage, they are an excellent choice for peaceful community aquariums. As a schooling species, they establish a pecking order, with males frequently flaring their fins in beautiful displays to attract females or establish dominance. They require well-oxygenated, moderately hard, alkaline water to thrive.
Delicate Blue-Eye
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Blue Rainbowfish
Melanotaenia caerulea
A small, highly active, and colorful schooling fish native to the Kikori River system in Papua New Guinea. They are peaceful but require ample swimming space and a school of their own kind to thrive. Like most rainbowfish, they appreciate well-oxygenated, flowing water and are excellent jumpers. Males develop a striking blue hue with reddish horizontal stripes.
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.
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.