Featherfin Rainbowfish / Threadfin Rainbowfish (Iriatherina werneri)

The Featherfin Rainbowfish, also known as the Threadfin Rainbowfish and formally identified as Iriatherina werneri, is a most enchanting species for freshwater aquarists. Its natural range extends across southern New Guinea and reaches into the northern tip of Australia, where it inhabits warm and tranquil waters rich in submerged vegetation. These environments often consist of shallow creeks, swamps, and quiet river margins filled with drifting plant matter, sun filtered light, and minimal current. In these placid spaces the species has evolved a refined body plan with slender proportions, large expressive eyes, and an almost weightless presence. Males display long filamentous fin extensions that move like fine silk in the slightest water movement, and females show a quieter beauty that complements the males rather than competing with them. This combination of elegance, gentle motion, and subtle natural color gives the species a uniquely artistic quality that can transform a planted aquarium into something that feels alive in a serene and contemplative way.

From a scientific and husbandry perspective the species remains straightforward once its basic preferences are understood. Adult size remains small at roughly three to five centimeters, and the fish thrives in stable water conditions that mirror its native habitats. A planted aquarium with soft to moderately hard water, a pH in the acidic to neutral range, and warm temperatures encourages confident behavior and full coloration. Gentle filtration helps maintain pristine clarity without introducing disruptive flow. The species is peaceful and social, so groups create natural displays of interaction and movement that highlight the species signature featherlike fins. Diet is equally important because Iriatherina werneri is a micropredator in the wild. Although the fish adapts readily to high quality prepared foods, it shows peak condition when given small live or frozen items such as baby brine shrimp or fine microprotein diets. When provided dense vegetation or spawning mops the species displays continuous parent­free reproduction, with males performing subtle but beautiful courtship movements that reveal its unique evolutionary adaptations.

For aquarists seeking a species that provides scientific interest, visual grace, and commercial reliability, the Featherfin Rainbowfish represents a standout choice. It suits planted tanks, gentle community settings, and specialty displays that emphasize motion and form rather than bold color alone. Its petite size makes it appropriate for modest aquaria when supported by strong water quality management, while its peaceful temperament allows aquarists to curate thoughtful mixed communities. The species also provides powerful aesthetic value because its extended fins and fluid swimming style give tanks a sense of weightless movement that feels almost atmospheric. Customers consistently appreciate that the fish shows its best behavior and color when kept in groups, and that it responds immediately to stable care and regular feeding. This fish does not ship individually bagged.

Common Name:  Featherfin Rainbowfish or Threadfin Rainbowfish
Scientific Name:  Iriatherina werneri
Country of Import:  Czech Republic
Prophylactic Treatment:  Erythromycin / Ich-X / Metro
Approximate Current Size:  2″ each
Temp/pH/TDS:  75F / 6.5 pH / 80

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