Pseudomugil ivantsoffi (Ivantsoff's Blue Eye)

11 August 2026

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Hailing from the pristine rainforest streams of West Papua and Papua New Guinea, Ivantsoff's Blue Eye is a captivating micro-predator. Known for its energetic schooling behavior and stunning neon-blue eyes contrasting with a vibrant golden-orange body, this peaceful nano fish is highly sought after by planted aquarium enthusiasts.

Pseudomugil ivantsoffi (Ivantsoff's Blue Eye)

Overview

Image of ivantsoff s blue eye pseudomugil ivantsoffi

Pseudomugil ivantsoffi, commonly known as Ivantsoff's Blue Eye, is a stunning and highly active nano fish belonging to the blue-eye family. Renowned for their brilliant coloration and the males' extravagant fin displays, they have become a prized centerpiece for nano and planted aquariums. Though small in stature, their energetic presence brings a dynamic and captivating element to any well-maintained setup.

Distribution and Habitat

This species is native to the remote, slow-flowing rainforest streams of the Timika region in West Papua, Indonesia, as well as parts of Papua New Guinea. They inhabit shallow, clear to tannin-stained waters heavily shaded by the dense jungle canopy. Their natural environment is characterized by dense aquatic vegetation, submerged roots, and leaf litter, which provide both shelter and rich foraging grounds.

Description of Ivantsoff's Blue Eye

Body shape:

They possess a slender, elongated, and slightly compressed body typical of the Pseudomugilidae family, designed for swift movements through the water column.

Color:

The body is a vibrant, semi-translucent golden-yellow to orange, adorned with a striking neon blue iridescent stripe along the dorsal ridge and a reddish tint near the gill plates.

Barbels:

They do not possess barbels.

Snout:

The snout is relatively short with a slightly upturned terminal mouth, perfectly adapted for feeding on insects near the water surface.

Eyes:

As their common name suggests, they feature large, captivating bright blue irises that contrast sharply with their warm body coloration.

Fins:

Males boast spectacular, enlarged dorsal and anal fins that are deeply colored in yellow-orange, speckled with prominent black spots, and edged in bright blue or white. Females have smaller, more transparent fins.

The Tail:

The caudal fin is moderately forked, sharing the yellowish-orange hue and dark speckling seen on the dorsal and anal fins.

Temper

This species is exceptionally peaceful. While males will frequently engage in flashy, elaborate sparring displays to establish dominance and attract females, these interactions are harmless and rarely result in physical injury.

Sociality

They are highly social shoaling fish that must be kept in groups of at least 6 to 8 individuals. Keeping them in a proper group ensures they feel secure, reduces stress, and encourages the males to exhibit their best colors and natural display behaviors.

Activity

Ivantsoff's Blue Eyes are incredibly active. They spend the majority of their time constantly darting and exploring through the upper and middle levels of the aquarium, making them a joy to observe.

Keeping and Caring for Ivantsoff's Blue Eye

Tank size:

A minimum aquarium size of 40 liters (10 gallons) is recommended to provide ample swimming space for a small group of these active swimmers.

Water Parameters:

Pristine water conditions are essential for the long-term health of this species. They are sensitive to fluctuating parameters and organic waste buildup.

Temperature

Maintain a stable water temperature between 24-28°C (75-82°F).

pH

They thrive in slightly acidic to neutral water, with an ideal pH range of 6.5-7.5.

Hardness

Keep the water soft to moderately hard, ideally between 5-12 dGH.

Ammonia, Nitrite, Nitrate

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

Lighting

Moderate to dim lighting is preferred. Floating plants can help diffuse bright lights, mimicking their shaded natural habitat and making the fish feel more secure.

Water flow

A gentle to moderate water flow is ideal, recreating the slow-moving currents of their native rainforest streams without exhausting them.

Decorations and Plants

A heavily planted tank with plenty of open swimming space is perfect. Incorporate driftwood, botanical elements, and leaf litter to replicate their natural environment, provide hiding spots, and encourage the growth of infusoria for natural grazing.

Diet

In the wild, they are micro-predators feeding on tiny insects, larvae, and zooplankton. In the aquarium, they are largely unfussy but require appropriately sized foods. They will readily accept high-quality crushed flakes, micro-pellets, and small live or frozen foods.

Some Feeding Tips

Offer small, frequent meals rather than one large one. Live baby brine shrimp, Daphnia, and microworms are excellent choices to enhance their vibrant colors, boost their immune system, and trigger breeding behavior.

Breeding

They are continuous egg-scatterers. To breed them successfully, provide a dedicated spawning tank equipped with a spawning mop or dense clumps of fine-leaved plants like Java Moss. Males will display intensely to females, leading them to the spawning site to deposit a few eggs daily. It is crucial to remove the eggs or the spawning medium regularly to a separate rearing container, as the adults will likely predate on their own eggs and fry. Fry require infusoria or specialized liquid fry food until they are large enough to accept newly hatched brine shrimp.

Conclusion

Ivantsoff's Blue Eye is a breathtaking addition to any peaceful, planted nano aquarium. Their energetic displays, vibrant golden-orange colors, and striking blue eyes make them a highly rewarding species for dedicated aquarists willing to maintain excellent water quality and a well-structured habitat.

Fish info

Care level: Moderate
Temperament: Peaceful
Adult size: 3-4 cm
Life expectancy: 2-3 years
Fish type: Rainbowfish
Temperature : 24-28°C
pH: 6.5-7.5
Color Form: Black, Blue, Orange, Red, Yellow

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