Max Size: 3 - 5cm

Threadfin Rainbowfish (Iriatherina werneri)

The Threadfin Rainbowfish is a small fish that holds excellent appeal. They are very peaceful but are not recommended for a community aquarium as they are easily outcompeted for food, and their fins may get nipped by other fish species.

They are best kept with their species or amongst other fish comparable in disposition and size.

The Threadfin Rainbowfish sport long, elegant fins, and the male displays a feather-like pattern, which is especially impressive.

These fish are silver in colour and a significant number of other colours all over their body, which is dependent on the environment, diet, etc.

When provided with perfect conditions, the Threadfin Rainbowfish can sparkle, featuring vibrant tints and shimmering scales. This fish can make a compelling addition to any tank.

Quick Facts
Scientific NameIriatherina werneri
Other NamesFeatherfin Rainbow
OriginsAustralia, Papua New Guinea
Aquarium LevelTop
Best kept asGroups 6+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH5 - 8
GH3 - 10
KH7 - 10
TDS20 - 220
71 - 86℉
21.7 - 30℃

Photos of the Threadfin Rainbowfish

Threadfin Rainbowfish
Threadfin Rainbowfish
Threadfin Rainbowfish
Threadfin Rainbowfish
Threadfin Rainbowfish Sparring
Threadfin Rainbowfish

Natural Habitat

Threadfin Rainbowfish are native to slow-moving streams, lagoons, freshwater marshes, billabongs and freshwater swamps, containing clear water and abundant macrophytes in New Guinea and Northern Australia and have also been found in the lakes Kala and Bosset.

They inhabit thickly vegetated areas associated with driftwood and Lilly pads which provide them with sun-filtered shade and shelter that the fish require.

What to feed the Threadfin Rainbowfish

Ideally, much of the Threadfin Rainbowfis's diet should incorporate live foods such as Daphnia, Artemia, Moina, micro worm, and copepods. However, small crushed floating dried foods such as flakes and granules are also accepted.

Just remember they have tiny mouths, so the food will need to be a suitable size.

How to sex the Threadfin Rainbowfish

Differentiating between males and females is easy with this species.

The males are silver in colour, have more ornate, larger fins than females, and display more intense colours, whereas the females are more golden toned and lack the fabulous fins.

How to breed the Threadfin Rainbowfish

Threadfin Rainbowfish is an egg-scatterer showing no parental care and will consume its eggs and fry if given the opportunity.

There are two ways you can breed. The first involves separating a single male and two to three females into a smaller tank set up with an air-powered sponge filter with a spawning medium such as a spawning mop or plants like java moss. These should be checked daily and removed to a separate hatching container if you find any eggs. This will allow more chance of fry survival.

Alternatively, you can maintain a colony of adults in a more widespread, fully-decorated set-up that should allow some fry to survive if well-planted.

The fry spends the early part of living close to the waters surface, so aquatic mosses attached to decor high in the water column or floating plants with trailing roots will more than likely produce the most favourable results.

When the females are spawning, the males will usually display to females under the coverage of floating plants. When the female is responsive, she will choose a site in the tank. This will usually be a bunch of fine-leaved vegetation or the roots of floating plants. Once selected, she will signal to the male by staying still in that exact spot. Both the female and male will then enter the medium to release milt and eggs.

The females deposit several eggs each day, and this will last around several days till she has deposited all of her eggs.

If there are other females in the same tank, the male will mate with them on the same day.

If you are lucky and your fry hatch, suitable tank conditions are essential because keeping them alive will also be a task in itself.

Other Rainbowfish of interest

Banded Rainbowfish(Melanotaenia trifasciata)
Boesemans Rainbowfish(Melanotaenia Boesemani)
Celebes Rainbowfish(Marosatherina ladigesi)
Dwarf Neon Rainbowfish(Melanotaenia praecox)
Forktail Blue Eye Rainbowfish(Pseudomugil furcatus)
Honey Blue Eye Rainbowfish(Pseudomugil Mellis)
View all Rainbowfish
Date Added: 28/08/2020 - Updated: 02/02/2022 16:36:24