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Fish Profiles | Threadfin Rainbowfish
Fish Profiles | Threadfin Rainbowfish
Here's a write-up on the dazzling Threadfin Rainbowfish (Iriatherina werneri), complete with tank specs and visuals to bring their elegance to life.
🌈 The Ethereal Beauty of Threadfin Rainbowfish
Threadfin Rainbowfish are among the most graceful freshwater species you can add to a planted aquarium. Native to Northern Australia and Papua New Guinea, these fish are prized for their elongated fins and shimmering hues that dance in the light. Males, in particular, boast extravagant dorsal and anal fins that trail like feathers, making them look like underwater ballerinas. Their peaceful nature and shoaling behavior make them ideal for community tanks, especially when kept in groups of six or more.
🏡 Tank Specifications for Thriving Threadfins
To keep Threadfin Rainbowfish healthy and vibrant, a minimum tank size of 60 litres (15–20 gallons) is recommended for a small group. These fish prefer soft, slightly acidic water with a pH between 6.0 and 7.5, and a temperature range of 24–28°C (75–82°F). Gentle filtration is key—strong currents can stress them out and damage their delicate fins. A dark substrate enhances their coloration, and a secure lid is essential as they’re known jumpers.
| Specification | Ideal Range |
|---|---|
| Tank Size | 60L (15–20 gallons) |
| Temperature | 24–28°C (75–82°F) |
| pH | 6.0–7.5 |
| Water Hardness | 5–19 dGH |
| Filtration | Gentle flow |
| Lighting | Moderate |
🌿 Aquascaping for Elegance and Comfort
Threadfins thrive in densely planted tanks with open swimming areas. Use plants like Java Fern, Anubias, and Water Sprite to mimic their natural habitat and provide hiding spots. Floating plants help diffuse light and offer cover, which reduces stress. Driftwood and smooth stones add structure without posing a risk to their fins. These fish are top-to-mid dwellers, so vertical space matters just as much as horizontal.
🍽️ Feeding and Social Behavior
Threadfin Rainbowfish are omnivores with a preference for tiny live or frozen foods like daphnia, baby brine shrimp, and micro worms. Their upward-facing mouths are adapted for surface feeding, so floating foods work best. They’re shy eaters and can be outcompeted by faster tank mates, so avoid housing them with boisterous or aggressive species. A ratio of 2–3 females per male helps reduce fin-flaring competition and encourages natural shoaling behavior.
🐣 Breeding and Lifespan
Breeding Threadfins is possible in a calm, well-maintained tank. Males perform elaborate fin displays to court females, and eggs are scattered over fine-leaved plants or spawning mops. Fry hatch in 8–12 days and require infusoria or microalgae as their first food due to their tiny mouths. With proper care, Threadfin Rainbowfish can live up to 4 years, offering years of shimmering beauty and peaceful companionship.
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Photo credit(s): Canva Pro Licence (main); Threadfin Rainbowfish (Iriatherina werneri) Male spreading his fin to tell another, there are my territory, chonasub woravichan (insert).
