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Main Index > Detailed Fish Profiles > Miscellaneous species > Threadfin Rainbowfish
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This profile was written by GunMan an active contributor to the site.  



Iriatherina werneri>

Iriatherina werneri



    The Threadfin Rainbowfish is a very peaceful schooling fish. It is a great choice for anyone who is looking for a Rainbowfish that stays fairly small.

Quick stats:

    Listed tank sizes are the minimum
    Size: Up to 1 in (4 cm)
    Tank: At least a 20 gallon long for a school.
    Strata: Mainly midwater to upper. Will feed at the top and bottom though.
    PH: PH recommendation 5.5 6.5
    Hardness: dH range 5 - 12° dGH
    Temperature: 73°F to 84°F (23°-29° C)


    Order: Atheriniformes (silversides)
    Class: Actinopterygii
    Family: Melanotaeniidae
    Genera: Iriatherina
    Species: werneri

Common name:

    Threadfin Rainbowfish , Featherfin Rainbowfish

Image gallery:
    Additional species photographs


    Badmans' Forum


    Australia: South-central New Guinea and Cape York Peninsula
General Body Form:

    All threadfins have a skinny body. The males develop the long beautiful fins from the dorsal and anus fins.


    Brownish with silvery reflections. The threadfins from New Guinea seem to be darker than the threadfins in Australia. Both sexes have dark backs, but the males are darker. I also feel like I should say that when looking at the Threadfins in stores, they are very sickly looking. Once you get them home though, their colors brighten incredibly.


    This fish can tend to be sensitive to nitrates and rollercoaster pH changes. Make sure you have a very stable tank before adding these fish.



    The Threadfin are not very fussy when it comes to feeding time, but make sure you vary their diet, and make sure that the food you are feeding them is small enough to fit in their throats. They have large mouths like all rainbows, but also have small throats like other rainbows.


    A heavily planted tank is recommended, but an open tank is too. The water flow should be slow. The plants will benefit from this also!


    This is not the easiest fish to breed, but it is possible. Have soft acidic water and fine leafed plants like Java moss. The male will dance around the female, and they will scatter their eggs on a fine leafed plant. They do eat their eggs sometimes, so remove the eggs if you want to keep the fry. These fry are one of the most smallest fry in the hobby. They are sometimes seen swimming at the top of the tank and require insuforia-like foods until their mouths grow larger.


    Most Rainbows are prone to skin flukes, parasitic infestations (protozoa, worms, etc.), ichthyobodo infection, parasitic infestations (protozoa, worms, etc.), bacterial infections (general), and bacterial diseases

Your comments:


Please remember that the following comments are personal experiences and may or may not apply to your setup. Use them as guide to help better understand your fish, like us all individuals will behave differently under different circumstances.


From: Brenton
A fantastic fish for the aquarium. I have found that the first week or so the fish tend to be sensitive to the tank but once established it is an easy fish to keep as long as the water parameters are constant. The males display at the females and other males is fun to watch as he flicks his fins frantically.





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