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Iriatherina werneri
Threadfin Rainbowfish

 Age of Aquariums > Freshwater Fish > Threadfin Rainbowfish - Iriatherina werneri

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Iriatherina_werneri_1.jpg (12kb)
Photo Credit: Shawna in CA

Name: Iriatherina werneri
Origin: New Guinea to Australia

Size Tank pH Temp
3 cm 40 L 6.4 28C


By far one of the most placid fish I have ever owned. These fish have never once attacked any other fish. All combat is ritualized by the males flicking their fins up and down, making it possible to house several males in one tank. They never nip each other's fins and, as these fish get older, their fins get longer and longer. Due to their streamlined bodies most fish can't keep up with them in a chase. Perfect fish.

Contributed by Steve

I am the manager of a large fish department at my pet store and I thought I'd give these a try. They are REALLY quite small, but none the less AWESOME fish when bought in schools. Their long fins in comparison to their little bodies do a good job complimenting a community tank. Easy fish to take care of, eats almost anything dropped into the tank. I rank them a 9/10 for a community fish.

Contributed by Cameron

I have six of these fish, and they are my favorites. My threadfins stick together about 97% of the time, and get along with my cories and swortails. They are very active, darting around the tank in a shoal. The males spend quite a bit of time establishing the pecking order, but other than that, they are very peaceful and I would highly recommend this fish to anyone with a community tank, or just someone looking for a nice shoal of fish for a small tank.

Contributed by Reiko

These are by far the coolest rainbowfish I've ever owned. I just bought 1 male and 2 females about a month ago. The male has awesome colors and is very protective over the females. Even though they are sorta expensive, they are perfect fish for someone with a community tank.

Contributed by Aaron

I have recently added four thread fin rainbows to my community tank. Very peaceful towards their tankmates, which is a contrast to the behavior used amongst themselves. Nippy at times, with the bulk of the aggressiveness displayed by the extention of their dorsal fin and threads. Once the pecking order is established, the alpha male keeps his clan in line with the occasional display of fins, but otherwise contented to stay in their reserved area. Easy to maintain and beautiful two-tone coloration, with enough speed to ward off any enemies, make these fish a great addition to any community tank.

Contributed by Alan Bourdon

I'd recommend this fish. I have 5 of them and males constantly display to each other. One reason why this fish may tend to die, as some new threadfin owners have said, is that they have narrow throats, although having big mouths. They should be fed with small particles of food rather than a large chunk of food. Also, avoid boisterous fish and fin nippers. Best kept in a species tank or fish with docile personalities.

Contributed by Blue

Threadfin Rainbowfish are amazing creatures. I myself have had five of them for the past 1 1/2 years. They are beautiful fish, and are extremely fun to watch.

Contributed by Drew

I bought 5 of those about a month ago. They are in a tank with live plants and they are absolutely beautiful and interesting to watch. The dominant male of the group shows much brighter colors due to his status. No major fights reported so far. One word of warning: do take great care in crushing their food into a fine powder when they're young. I lost one two days ago. One minute he's perfectly fine eating...the next he's lying at the bottom of the tank, dead. What they say about them choaking on food is true! I buy micro pellets and crush them. They also go wild for freeze dried bloodworms. I feed them the fine powder at the bottom of the box.

Contributed by Izzy

I have a couple of threadfins in my 110 L aquarium, and they are the most peaceful fish. They love to eat, although they have to go for the smaller bits of food because they can't eat the big pieces. Their slate-ish blue-grey color is very stunning, and they have bright blue eyes. Their dorsal fins are fun to watch, as they flicker up and down as they swim and/or as the males show. I'd highly recommend this fish.

Contributed by Minsoo

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