Threadfin Rainbow – Iriatherina werneri

Threadfin Rainbowfish (Iriatherina werneri) are very interesting and unique rainbows. Females are pale gold overall with some faint accents and slender bodies. Males feature a pale gold color with possible reddish or yellow accents (a male is pictured above). The finnage is what makes these rainbows so stunning. Like most rainbows, these have double dorsals. The first dorsal is very high and fan-shaped. The second dorsal has elongated filaments. The anal and pelvic fins also feature elongated filaments, usually dark red to black in color. The caudal fin is deeply v-shaped and features elongated filaments, as well. The female may feature some of the same colors and fins, though much more subdued.

Rainbow fish make a great additions to a community tank. Their sleek, oblong bodies are made for speed, and they constantly make laps back and forth through the aquarium. Many species grow to 3 to 4 inches in length and a small group of these fish can add extraordinary color to your tank. While juveniles may have a relatively drab appearance, they truly live up to their name as they mature. Males are especially colorful in most species, developing vibrant yellow, orange, red, blue and green shades, some with stripes or bars. Both males and females should be kept in the aquarium so males retain their vibrant hues. Rainbows are schooling fish, and it is best to keep them in groups of at least four so they feel secure and stay in the open.

New species and variations of Rainbowfish are being discovered and imported for aquarium use each year as they gain in popularity. The largest and most well-known genus is Melanotaenia, and species from genus Pseudomugil are also frequently offered. Other less common species may also be seen in our tanks from time to time. Most Rainbowfish originate in lakes, streams and rivers of Australia, Southeast Asia, and other islands in the region.

Rainbows can be kept with a wide variety of community tank mates like tetras, danios, rasboras, others Rainbows, dwarf cichlids and similar fish. They are not picky eaters and will generally accept flakes, pellets and a range of frozen foods like mysis, brine shrimp and other similar items. They will not bother plants and are ideal for planted aquariums. A long aquarium is best to give them plenty of distance to swim back and forth in the tank.