Iriatherina werneri

About This Species

The Threadfin Rainbowfish, also known by the equally fitting name Featherfin Rainbowfish, is a stunning gem from the slow-moving, heavily vegetated waters of Australia and New Guinea. This diminutive species is a true spectacle in a well-maintained aquarium, celebrated not for its size, but for its extraordinary finnage and vibrant, shimmering colors. The most captivating feature belongs to the males, who sport elaborate, thread-like extensions on their second dorsal and anal fins, which they flare dramatically during displays of courtship or territorial sparring. Females are more subdued in color and fin structure but are essential for the social dynamics of the group. Creating the ideal habitat is key to their well-being. They thrive in a mature, well-planted aquarium with gentle water flow, which mimics the swamps and quiet streams of their native environment. Floating plants are highly recommended as they help to diffuse overhead lighting, making these somewhat shy fish feel more secure. A dark substrate can also help to accentuate their subtle yet brilliant colors. Due to their active nature and tendency to jump when startled, a secure lid is a necessity. While they can adapt to a range of water parameters, stability is more important than chasing exact numbers. They prefer soft, slightly acidic to neutral water that is kept immaculately clean. As active swimmers occupying the top and middle regions of the tank, they must be kept in a group. A lone individual will be stressed and reclusive. In a school, their fascinating social behaviors emerge, with males constantly posturing and showing off to one another and to the females. Their peaceful temperament makes them suitable for community tanks, but tank mates must be chosen with care. Ideal companions include other small, peaceful species like dwarf rasboras, celestial pearl danios, pygmy corydoras, and Neocaridina shrimp. Avoid boisterous or fin-nipping fish that could intimidate them or damage their delicate fins. Feeding these fish is straightforward, but their small mouths must be taken into account. Their omnivorous diet should consist of high-quality, crushed flake foods and micro-pellets, supplemented frequently with small frozen or live foods like daphnia, cyclops, and newly hatched brine shrimp. This varied diet is crucial for maintaining their health and vibrant coloration. While not for the absolute beginner, the Threadfin Rainbowfish offers a deeply rewarding experience for the aquarist willing to provide the specific conditions it needs to flourish.