Pseudomugil luminatus – Red neon blue-eye

The Red Neon Blue-eye is a stunning, small freshwater fish prized in the aquarium hobby for its incredible color, energetic behavior, and manageable size. It’s a relatively recent discovery but has quickly become a favorite among nano tank and biotope enthusiasts.

Overview & Natural History

Scientific Name: Pseudomugil luminatus
Common Names: Red Neon Blue-eye, Neon Blue-eye, Crimson-spotted Blue-eye
Discovery: First described scientifically in 1998 by Allen, Hadiaty, and Unmack. It was discovered in the Timika region of southern New Guinea (Indonesia, Papua Province).
Habitat: They inhabit slow-moving or still waters in coastal lowland swamps, streams, and tributaries. These environments are typically blackwater, with tea-stained, acidic water from decaying leaf litter and tannins, over soft, sandy substrates.

Physical Appearance

This fish is a true gem, with appearance varying significantly between sexes.

Size: Very small, typically reaching a maximum size of 3 cm (1.2 inches).
Body: Slender and slightly elongated.
Coloration (Males): This is where the fish gets its name. Males are spectacularly colored.
- Their body is a translucent silvery-yellow.
- The fins are their main feature: The dorsal, anal, and caudal fins are bright yellow and often edged in white. The tips of the fins are adorned with vivid, crimson-red spots.
- Their eyes are a brilliant, electric blue, a characteristic of the Pseudomugil genus.
- During courtship, colors become even more intense.
Coloration (Females): Females are significantly plainer. They possess the same beautiful blue eyes but lack the extravagant fin colors and spotting. Their bodies are more silvery and translucent, and they are generally rounder, especially when carrying eggs.

Behavior & Temperament

Temperament: Peaceful, inquisitive, and non-aggressive. They are perfect community fish for tanks with other small, gentle species.
Activity: Highly active and energetic swimmers. They are almost constantly in motion, dancing and displaying to each other. They do not school tightly like tetras but rather shoal loosely, preferring the safety of a group while investigating their territory.
Swimming Level: Prefer the top to middle levels of the aquarium.

Aquarium Care

Tank Size: While a small group can be kept in a 10-gallon tank, a 15-gallon or 20-gallon long aquarium is ideal. The longer footprint provides much-needed swimming space and reduces stress.

Water Parameters:

Temperature: 22°C – 28°C (72°F – 82°F)
pH: 5.5 – 7.5 (They prefer slightly acidic to neutral water)
Hardness: Soft to moderately hard water is acceptable, but they thrive in softer conditions.
Cleanliness: They are sensitive to deteriorating water quality. Regular weekly water changes (20-30%) are essential. Avoid strong currents.

Tank Setup:

Substrate: Dark sand or fine gravel to mimic their natural habitat and make their colors pop.
Decor: A heavily planted tank is ideal. Use live plants like Java moss, Hornwort, and floating plants (e.g., Frogbit, Salvinia) to provide cover and security. Floating plants help dim the light and encourage displaying behavior.
Additions: Driftwood, Indian Almond Leaves, and Alder Cones are highly recommended. They release beneficial tannins, lower pH, and create a natural blackwater environment. The leaf litter also provides microfauna for the fish to forage on.

Diet

They are micropredators. In the wild, they feed on tiny insects, zooplankton, and algae.

In the aquarium, they should be fed small, high-quality foods.
Staple Diet: High-quality micro-pellets and crushed flake food.
Preferred Foods: They thrive on and their colors are enhanced by live and frozen foods such as baby brine shrimp, microworms, daphnia, and vinegar eels.
Feed small amounts 2-3 times daily.

Tankmates

Excellent community fish when kept with appropriate species. Their small size and peaceful nature mean they can be easily intimidated or eaten.

Ideal Tankmates: Other small, peaceful fish like:
- Small tetras (e.g., Ember Tetra)
- Dwarf Corydoras (e.g., Pygmy Cory)
- Otocinclus Catfish
- Small, peaceful rasboras (e.g., Chili Rasbora)
- They do best in a species-only tank or with shrimp (Neocaridina/Caridina).
Tankmates to Avoid: Any large, aggressive, or boisterous fish that may see them as food, such as most cichlids, larger barbs, or predatory catfish.

Breeding

Red Neon Blue-eyes are continuous spawners and can be bred relatively easily in a dedicated setup.

Conditioning: Separate males and females for a week or two and feed them heavily with live foods.
Spawning Tank: Set up a small tank with soft, acidic water, Java moss or a spawning mop, and gentle filtration (air-powered sponge filter). The adults will eat eggs and fry, so the moss/mop is essential for the eggs to fall into and be protected.
Spawning: Introduce the conditioned fish. Males will display vigorously to females. Spawning occurs daily, with females depositing a small number of eggs (10-20) in the moss.
Raising Fry: Either remove the adults or carefully move the egg-laden moss/mop to a separate rearing tank. Eggs hatch in 10-14 days (depending on temperature). Feed the microscopic fry infusoria or commercial fry food for the first few days, then transition to baby brine shrimp.

Lifespan

Their lifespan is relatively short. They typically live for 1 to 2 years, occasionally up to 3 years in optimal conditions.

Summary Table

Category	Details
Scientific Name	Pseudomugil luminatus
Common Name	Red Neon Blue-eye
Max Size	3 cm (1.2 inches)
Temperament	Peaceful, Shoaling
Tank Size	40 Litres / 10 Gallons (minimum), larger preferred
Diet	Omnivore (Micropredator); prefers small live/frozen foods
Water Temperature	22°C – 28°C (72°F – 82°F)
pH	5.5 – 7.5
Difficulty	Easy to Intermediate (sensitive to water quality)
Breeding	Easy; egg-scatterer, continuous spawner

In conclusion, the Red Neon Blue-eye is a captivating and rewarding fish that brings a splash of brilliant color and fascinating behavior to a well-maintained peaceful aquarium.