Threadfin Rainbowfish

Threadfin Rainbowfish (Iriatherina werneri)

The Threadfin Rainbowfish is a small, elegant, and peaceful freshwater fish native to Australia and New Guinea. These striking fish boast elongated, thread-like fins and iridescent scales that shimmer in shades of green, yellow, and blue. Males display more vibrant colors and longer fins compared to the females.

Threadfin Rainbowfish typically grow to around 2 inches in length and are best kept in schools of at least 6 to ensure their well-being and encourage natural behavior. These peaceful fish are ideal for community tanks with other non-aggressive species of a similar size, such as small tetras, rasboras, and peaceful bottom-dwellers like Corydoras catfish.

Threadfin Rainbowfish are omnivores, feeding on a varied diet consisting of high-quality flake food, micro-pellets, and live or frozen foods such as daphnia, brine shrimp, and bloodworms. A diverse diet will contribute to their overall health and maintain their stunning colors.

A well-planted aquarium with plenty of hiding spots and open swimming spaces is crucial for the Threadfin Rainbowfish. Rainbowfish are active swimmers and require an aquarium with plenty of room to move about and abundant plant life to give them a sense of security. Their natural habitat features various leggy plants like Dwarf Sagittaria, Vallisneria, and Anubias, which are easy for the fish to navigate through. When arranging the plants, ensure to leave unobstructed open swimming areas. A substrate consisting of rocks or sand with driftwood can help recreate their native environment, but the tank floor is of lesser importance, as they usually swim in the middle levels. The addition of floating plants to diffuse the light entering the tank also seems to be appreciated and adds a more natural feel.

Maintaining a clean and well-oxygenated tank is crucial for Threadfin Rainbowfish, as their water should be free from nitrates and ammonia. They prefer moderate water currents and appreciate a substantial water flow, making a power filter an excellent choice for their aquarium.

A minimum tank size of 20 gallons is recommended, with 30 gallons or larger in community aquariums. The ideal water parameters for these fish include a pH of 6.0-7.5, a hardness of 3-12 dGH, and a temperature range of 75-82°F (24-28°C).

Do not add this fish to a biologically immature aquarium, as it can be susceptible to swings in water chemistry.