Pseudomugil furcatus (Forktail Blue-eye)

13 July 2026

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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

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