Threadfin Rainbowfish (Iriatherina werneri)

Threadfin Rainbowfish Elegant Finnage Peaceful Nano Rainbow Planted Aquarium Showpiece

Threadfin Rainbowfish (Iriatherina werneri) are delicate, eye-catching freshwater fish prized for their long, flowing fin filaments and graceful swimming style. Males display especially striking extended dorsal and anal fins, often accented with red, yellow, or blue highlights that shimmer under proper lighting.

Threadfins are peaceful and thrive in calm, well-planted aquariums with gentle flow. They are best kept in groups, where males will display to one another without aggression. Their refined appearance and gentle nature make them a favorite for planted tanks, display aquariums, and aquascapes.

While slightly more sensitive than standard community fish, Threadfin Rainbows reward attentive care with constant movement and stunning elegance.

Key Features & Benefits

• Long, Flowing Thread-Like Fins
• Subtle Iridescent & Pastel Colors
• Peaceful & Community-Safe
• Perfect for Planted & Aquascaped Tanks
• Beautiful Schooling & Display Behavior
• Ideal for Calm, Well-Maintained Aquariums

Care & Tank Requirements

Scientific Name: Iriatherina werneri
Common Name: Threadfin Rainbowfish
Adult Size: ~2 inches
Temperament: Peaceful
Schooling: Yes (recommended 6+)

Tank Size: 20 gallons or larger
Temperature: 7582°F
pH Range: 6.07.5
Water Hardness: Soft to moderate
Flow: Gentle to moderate

Diet:

• Fine flakes or micro pellets
• Frozen/live foods (baby brine shrimp, daphnia, cyclops)

Tank Mates:

• Small tetras
• Corydoras
• Rasboras
• Otocinclus
• Other peaceful nano fish

Avoid aggressive or fin-nipping species.

Care Tips

• Keep males with multiple females to reduce stress
• Gentle filtration preserves fin condition
• Stable water quality is key for long fin health
• Best coloration under soft lighting and planted cover

FAQ

Are Threadfin Rainbows beginner friendly?
Best for intermediate hobbyists due to their sensitivity to water quality.

Do males fight?
No — males display without aggression.

Can they live in community tanks?
Yes, with peaceful tank mates only.

Do they need a planted tank?
Strongly recommended for comfort and display behavior.

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