THREADFIN RAINBOW (Iriatherina werneri) 1.25″

Threadfin Rainbow for Sale in Canada

The Threadfin Rainbow (Iriatherina werneri) is one of the most delicate, elegant, and visually stunning nano freshwater fish available in the aquarium hobby. Known for its flowing filament-like fins, shimmering body, and graceful swimming behavior, this species is highly prized by aquascapers and planted tank enthusiasts across Canada. At approximately 1.25 inches, these fish are still in their ideal display size range, showing early signs of their famous elongated fin extensions.

Native to slow-moving, heavily vegetated waters of northern Australia and New Guinea, Threadfin Rainbows thrive in calm, warm, and well-planted aquariums. Their peaceful nature and mesmerizing finnage make them a true centerpiece in nano and aquascaped freshwater setups.

Why Choose Threadfin Rainbow Fish?

Threadfin Rainbows are not just beautiful—they are one of the most elegant schooling nano fish in the aquarium hobby.

Stunning Filament Fins

Mature males develop long, thread-like extensions on their dorsal and anal fins, creating a flowing, almost “floating ribbon” effect in the water. Even at 1.25″, young males begin developing these delicate extensions, hinting at their full adult beauty.

When kept in groups, these fins create a synchronized drifting motion that looks spectacular in planted aquariums with gentle water flow.

Delicate but Highly Elegant Appearance

Their slender, translucent bodies reflect soft shades of silver, gold, and pastel tones depending on lighting. Combined with their delicate fins, they bring a sense of calm movement and refinement to aquascapes.

Ideal Aquarium Setup

Threadfin Rainbows require stable, carefully maintained aquariums to thrive and show their best coloration and finnage.

Recommended Tank Conditions

• Temperature: 75°F – 82°F (24°C – 28°C)
• pH: 6.0 – 7.5
• Soft to moderately soft water
• Very gentle flow (low current preferred)
• Heavily planted aquarium
• Dark substrate recommended for contrast
• Minimum group size: 6–10 fish

They are sensitive to sudden water changes, so stability is more important than anything else.

Ideal Tank Mates

Threadfin Rainbows are extremely peaceful and should only be kept with other calm species.

Compatible Tank Mates

• Pygmy Corydoras
• Ember Tetras
• Chili Rasboras
• Otocinclus
• Small shrimp (Neocaridina, Amano)
• Other peaceful nano fish

Avoid aggressive or fast-feeding fish that may outcompete them for food.

Feeding Requirements

Threadfin Rainbows have small mouths and require fine, high-quality foods.

Recommended Diet

• Micro pellets
• Powdered flakes
• Baby brine shrimp
• Cyclops
• Daphnia
• Live or frozen micro foods

Frequent small feedings help maintain health and condition, especially for fin development.

Behavior and Schooling

These fish are best displayed in groups where males actively flare and display their fins. Males often compete in gentle displays rather than aggression, creating a mesmerizing “dance” effect in the aquarium.

A well-maintained group will constantly interact in mid-water and upper levels, making them ideal for nature-style aquascapes.

Why Buy Threadfin Rainbow from Monster Aquarium Canada?

Monster Aquarium Canada supplies healthy, high-quality Threadfin Rainbow fish selected for fin development, coloration, and condition. Each fish is carefully acclimated to ensure stability during shipping and successful transition into planted aquariums.

Whether you’re building a high-end aquascape, nano planted tank, or specialty display aquarium, Iriatherina werneri delivers unmatched elegance and movement.

Frequently Asked Questions

How big do Threadfin Rainbows get?

They typically reach about 1.5 to 2 inches in body length, not including fin extensions.

How many should be kept together?

A group of at least 6–10 is recommended for natural behavior and best display.

Are Threadfin Rainbows hard to keep?

They are moderately delicate and require stable water conditions, making them better suited for intermediate aquarists.

Can they live with shrimp?

Yes. They are generally shrimp-safe and ideal for planted nano shrimp tanks.

Do males and females look different?

Yes. Males develop long filament fins, while females remain shorter-finned and slightly rounder.