Threadfin Rainbow

The Threadfin Rainbowfish (Iriatherina werneri) is a delicate and incredibly beautiful nano fish, prized for its flowing, thread-like fins and shimmering coloration. Native to slow-moving waters in northern Australia and New Guinea, this species is a top choice for peaceful, planted aquariums.

🐟 Threadfin Rainbowfish – Quick Profile

• Scientific Name: Iriatherina werneri
• Common Names: Threadfin Rainbow, Featherfin Rainbowfish
• Size: 1.5–2 inches
• Lifespan: 3–5 years
• Temperament: Very peaceful, best in groups

🌈 Appearance:

• Males display long, thread-like fin extensions and dramatic fan-shaped dorsal and anal fins
• Iridescent body with hints of gold, blue, or silver (color varies with mood and lighting)
• Females are smaller with shorter fins and duller coloration

✅ Why Keep Them?

• Ideal for nano and community tanks
• Peaceful and shy—do best in schools of 6+
• Great choice for heavily planted aquascapes
• Active top-level swimmers with mesmerizing display behavior

💧 Tank Requirements:

• Tank Size: 10 gallons minimum (20+ preferred for groups)
• Temperature: 74–82°F (23–28°C)
• pH: 6.0–7.5
• Water Hardness: Soft to moderate
• Tank Setup: Fine plants, gentle filtration, open swimming space

🍽️ Diet:

• Micro-predators – feed live/frozen baby brine shrimp, daphnia, micro worms
• Accepts high-quality micro pellets and fine flake foods

🐣 Breeding:

• Egg scatterers – males display to attract females
• Will spawn over fine-leaved plants or spawning mops
• Best bred in species-only tanks due to fry sensitivity