Pseudomugil furcatus (Forktail Blue-eye)

13 July 2026

614

The Forktail Blue-eye (Pseudomugil furcatus) is a captivating, highly active nano fish native to the rainforest streams of Papua New Guinea. Renowned for their striking neon blue eyes, bright yellow finnage, and peaceful schooling behavior, they have become incredibly popular additions to planted community aquariums among dedicated aquarists.

Pseudomugil furcatus (Forktail Blue-eye)

Overview

Image of fork tailed blue eye pseudomugil furcatus

The Forktail Blue-eye, scientifically known as Pseudomugil furcatus, is an incredibly energetic and visually stunning freshwater species. Belonging to the Pseudomugilidae family, these diminutive fish are highly sought after for their vivid contrasts, particularly the bright neon-blue eyes and lively yellow accents across their fins. They are a fantastic choice for aquarists looking to add movement and a flash of color to a planted nano or community tank.

Distribution and Habitat

This species is endemic to the eastern regions of Papua New Guinea, specifically found in the Peria Creek and the Kwagira River drainage. In their natural habitat, they inhabit clear, slow-to-moderately flowing rainforest streams with dense vegetation. The water in these regions is typically slightly alkaline and rich in oxygen, shaded by the dense jungle canopy above which provides a dappled lighting effect.

Description of Forktail Blue-eye

As seen in the provided images, the Forktail Blue-eye boasts a delicate yet striking appearance that makes it stand out in any aquatic setting.

Body shape:

They possess a slender, elongated, and slightly compressed body designed for swift, darting movements through the water column.

Color:

The main body is somewhat translucent to silvery-grey, often showcasing a prominent yellowish or bright orange flush along the belly and lower half of the body.

Barbels:

This species does not possess any barbels.

Snout:

The snout is relatively short with a small, slightly upward-pointing mouth, indicating their preference for feeding near the water surface.

Eyes:

Their most defining feature is their large, striking, iridescent neon-blue eyes that contrast beautifully with their yellow and orange body hues.

Fins:

The fins are highly decorative. The pectoral fins point upwards like small wings with yellow tips. The dorsal and anal fins are predominantly transparent but feature bold, bright yellow margins and occasional dark inner edges. Males have much more extended and vibrant fins than females.

The Tail:

They feature a deeply forked caudal fin (tail), which is bordered with distinct bright yellow tips and dark, almost black, inner margins.

Temper

They are known for their completely peaceful temperament. They do not bother other species and are perfectly suited for a peaceful community aquarium alongside other small, non-aggressive fish.

Sociality

Forktail Blue-eyes are highly social, schooling fish. They should be kept in groups of at least 6 to 8 individuals, though larger groups are highly recommended. In a group, males will display their best colors and flare their fins to establish hierarchy and impress females, providing a spectacular show without causing actual harm to one another.

Activity

These fish are extremely active and constantly on the move. They typically occupy the middle to top levels of the aquarium, darting around plants and playfully chasing each other throughout the day.

Keeping and Caring for Forktail Blue-eye

While not overly difficult to keep, they do require stable water conditions and a well-maintained environment to thrive and display their best colors. Due to their active nature, they need ample swimming space despite their small size.

Tank size:

A minimum tank size of 15 to 20 gallons is recommended. The length of the tank is more important than the height, as they need horizontal swimming space to accommodate their energetic darting.

Water Parameters:

Consistency is key. They are sensitive to sudden fluctuations in water chemistry and require a mature, fully cycled aquarium.

Temperature

They prefer warmer tropical waters, ideally kept between 24°C and 27°C (75°F - 81°F).

pH

Unlike many other tropical fish, they naturally prefer slightly alkaline conditions. A pH range of 7.0 to 8.0 is ideal.

Hardness

They do best in moderately hard water, with a general hardness (GH) of 5 to 15 dGH.

Ammonia, Nitrite, Nitrate

Ammonia and Nitrite must always be at 0 ppm. Nitrates should be kept as low as possible, ideally below 20 ppm, through regular water changes.

Lighting

Moderate lighting is best. If the lighting is too bright, floating plants can be used to diffuse it, replicating the dappled sunlight of their native jungle streams.

Water flow

They appreciate a moderate water flow. A filter that provides a gentle to moderate current will mimic their natural riverine habitat and encourage their playful swimming behavior.

Decorations and Plants

A heavily planted tank is highly recommended. Use a dark substrate to make their colors pop. Provide dense thickets of stem plants and mosses for cover, but ensure you leave plenty of open swimming space in the upper and middle water column.

Diet

In the wild, they are micro-predators, feeding on tiny insects, zooplankton, and invertebrate larvae. In the aquarium, they are omnivorous and will readily accept high-quality dry foods, but their diet should be supplemented with live or frozen foods to maintain their vibrant colors and overall health. Excellent choices include baby brine shrimp, daphnia, cyclops, and micro-worms.

Some Feeding Tips

Because they have very small, upward-pointing mouths, ensure all food is appropriately sized. Micro-pellets or crushed high-quality flakes are ideal. It is best to feed them small amounts two times a day rather than one large meal.

Breeding

Breeding the Forktail Blue-eye is relatively straightforward in a dedicated setup. They are continuous egg scatterers. To breed them, provide a small tank with slightly alkaline water, gentle filtration (like a sponge filter), and plenty of spawning mops or dense clumps of Java Moss. Condition the breeders with live foods. Females will deposit a few adhesive eggs daily among the moss or mops. Because the adults may eat the eggs, it is best to remove the spawning medium to a separate hatching container every few days. The fry are incredibly tiny upon hatching (around 10-15 days later) and require infusoria or specialized liquid fry food until they are large enough to accept baby brine shrimp.

Conclusion

The Forktail Blue-eye is an absolute gem for the freshwater aquarium. With their mesmerizing blue eyes, vibrant yellow accents, and lively personalities, they bring an unparalleled dynamic energy to a planted tank. By providing them with clean, slightly alkaline water and a proper schooling group, aquarists will be rewarded with a spectacular, constantly moving display.

Fish info

Care level: Moderate
Temperament: Peaceful
Adult size: 5-6 cm
Life expectancy: 2-3 years
Fish type: Rainbowfish
Temperature : 24-27°C
pH: 7.0-8.0
Color Form: Blue, Clear, Orange, Silver, Yellow

Related on Fishs

Leave your comments

Latest on Fishs

Dwarf Gourami Red (Trichogaster lalius)

Easy - Moderate

Asian labyrinth fish

The red dwarf gourami is a selectively bred color form of the dwarf gourami, a small labyrinth fish formerly widely known as Colisa lalia. It is suited to mature, planted community aquariums with gentle water movement and calm tank mates. Males can be territorial, especially when kept with females in confined conditions, so cover, visual barriers, and careful observation are important for a pair.
Cockatoo Cichlid Red (Apistogramma cacatuoides)

Moderate

South American dwarf cichlid

The Cockatoo Cichlid is a small South American dwarf cichlid valued for its personality, breeding behavior and colorful finnage. Apistogramma cacatuoides is generally adaptable when provided with clean, stable water, cover and a soft substrate. Males are larger and more vividly marked than females, while pairs become territorial around spawning sites. The supplied “red” designation most likely refers to a selectively bred color form; exact strain and sex confirmation cannot be established from the listing alone.
Discus (Symphysodon aequifasciatus) Care Guide

Difficult

South American freshwater cichlid

Symphysodon aequifasciatus is a large, laterally compressed cichlid from the Amazon Basin, valued for its calm behavior and striking disc-shaped body. It requires warm, clean, stable water and careful feeding, making it better suited to experienced aquarists. The supplied images show yellow, orange, red, white and dark color forms; cultivated strains can vary considerably, so exact variety identification from images alone is uncertain. Discus are social fish and generally thrive in groups rather than as isolated specimens.
Cape Lopez Killifish (Aphyosemion australe)

Moderate

West African non-annual killifish

The Cape Lopez killifish is a small, peaceful West African freshwater fish prized for its patterned body, flowing fins and manageable size. It inhabits slow-moving and temporary waters around coastal Gabon, including the Cape Lopez region. The supplied trade description identifies a pair as “Cape Lopez splendid carpets,” but this wording may describe a commercial strain rather than a formally recognized taxon. The image appears to show an orange form, so exact strain identification should be confirmed with the breeder or supplier.
Burton’s Mouthbrooder (Astatotilapia burtoni)

Moderate

East African haplochromine cichlid

Burton’s mouthbrooder, Astatotilapia burtoni, is a moderately aggressive East African haplochromine cichlid known for strong social hierarchies and maternal mouthbrooding. Males become more vividly patterned and defend territories, while females are generally less colorful and carry eggs and fry in the mouth. A pair requires a spacious, well-filtered aquarium with rocky cover, alkaline water and carefully selected tank mates. The supplied identification is consistent with Astatotilapia burtoni, although sex and locality form cannot be confirmed from the photographs alone.
Cyrtocara moorii (Blue Dolphin Cichlid) Care Guide

Moderate

Lake Malawi haplochromine cichlid

Cyrtocara moorii is a large, distinctive haplochromine cichlid from Lake Malawi, recognised for its blue adult coloration and rounded forehead, which becomes more pronounced with age. It is a maternal mouthbrooder and is generally less aggressive than many Malawi mbuna, but its size and territorial breeding behaviour require a spacious aquarium. The supplied images appear consistent with blue C. moorii, although photographs cannot confirm sex, locality, or whether the fish form a true bonded pair.
Blue Dwarf Gourami Pair (Trichogaster lalius)

Easy - Moderate

Peaceful labyrinth fish

The blue dwarf gourami is a selectively colored form of a small labyrinth fish native to the Indian subcontinent. It spends much of its time in the upper and middle aquarium, using its specialized labyrinth organ to breathe atmospheric air. Males can become territorial, especially when nesting, so a planted aquarium with calm tank mates, gentle flow, and surface cover is important. The supplied name uses Trichopodus lalius; Trichogaster lalius is the commonly used current combination.
Blue Acara (Aequidens pulcher)

Moderate

South American freshwater cichlid

The supplied label identifies these fish as Blue Acara, Aequidens pulcher, a South American freshwater cichlid often placed in the genus Andinoacara in current aquarium literature. The photograph is consistent with a blue acara, although a definitive identification cannot be confirmed from one image alone. This pair requires a spacious aquarium, stable water quality, hiding places and careful observation during breeding, when territorial behavior becomes stronger.
Julidochromis transcriptus: Black-and-White Slender Cichlid

Moderate

Lake Tanganyika rock-dwelling cichlid

Julidochromis transcriptus is a small rock-dwelling cichlid from Lake Tanganyika, recognized by its compact, elongated body and irregular black-and-white pattern. It is a territorial cave dweller that is best kept as an established pair in a carefully structured aquarium. The supplied fish are identified as a DNZ pair, although sex, collection locality, and precise geographic form cannot be verified from the supplied material alone.
Azur Cichlid (Sciaenochromis fryeri) Care Guide

Moderate

Lake Malawi haplochromine cichlid

The Azur cichlid is commonly sold as Sciaenochromis fryeri, a predatory haplochromine cichlid from Lake Malawi. Mature males develop vivid electric-blue coloration, while females and juveniles are generally less intensely colored. This fish is moderately aggressive and needs a spacious aquarium with rocky structure, alkaline, mineral-rich water, and carefully selected tank mates. The supplied source describes a DNZ pair, but sex and exact locality cannot be confirmed from the images alone. Identification confidence is therefore good but not absolute.
Marble Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The marble angelfish is a captive-bred color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular black patterning. It needs a mature, spacious aquarium with excellent water quality, warm water and suitable tank mates. Although generally manageable, adults establish territories and may become assertive when pairing or spawning. The supplied source identifies two marble angelfish; exact lineage and strain details cannot be confirmed from the available information.
Gold Angelfish, Pterophyllum scalare

Moderate

Freshwater South American cichlid

The Gold Angelfish is an ornamental colour form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its graceful movement and parental care. It needs a mature, spacious aquarium with substantial vertical clearance, stable warm water and carefully chosen tank mates. The supplied source identifies two fish as Gold Angelfish, although the accompanying images show several angelfish colour and fin forms, so the exact appearance of the supplied specimens cannot be confirmed from the images alone.
Zebra Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The Zebra Angelfish is a selectively bred form of Pterophyllum scalare, recognised by a silvery body with several dark vertical bars and the tall, laterally compressed shape typical of freshwater angelfish. The supplied images also show other angelfish colour forms, so the exact appearance of the listed pair cannot be confirmed from the image set alone. This South American cichlid is generally manageable for experienced community keepers, but its size, territorial breeding behaviour and need for a tall aquarium should be planned for carefully.
Black Angelfish (Pterophyllum scalare)

Moderate

South American freshwater cichlid

The supplied record identifies two black angelfish, most likely a domestic color form of Pterophyllum scalare. The photographs show several angelfish color patterns, so they should not be treated as proof that every pictured fish is black or that all belong to the same strain. Black angelfish retain the tall, laterally compressed body and extended fins typical of freshwater angelfish. They need a tall, mature aquarium, stable warm water, a varied diet, and carefully selected tank mates.
White Marble Angelfish (Pterophyllum scalare)

Moderate

Freshwater cichlid

The white marble angelfish is a selectively bred aquarium color form of Pterophyllum scalare, a tall-bodied South American cichlid valued for its elegant fins and distinctive irregular dark marbling. It is generally peaceful when young but can become territorial, especially when paired for spawning. Successful care depends on a tall aquarium, excellent water quality, suitable tank mates, and a varied carnivorous-omnivorous diet. The exact genetic strain shown cannot be confirmed from photographs alone.
Freshwater Angelfish Mix (Pterophyllum scalare)

Moderate

Freshwater cichlid

Freshwater angelfish are tall-bodied South American cichlids valued for their graceful movement and wide range of captive color forms. The supplied source identifies a mixed group as Pterophyllum scalare; the photographs show several forms, including striped, black, orange, white, silver and blue-toned fish. They are manageable for experienced beginners, but their adult height, territorial breeding behavior and tendency to eat small tank mates require thoughtful aquarium planning.