Featherfin Rainbowfish (Iriatherina werneri)

American-Bred Fish

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The featherfin rainbowfish, or threadfin rainbowfish, is a dwarf rainbowfish that was originally collected in Papua New Guinea. It has since been collected from basins near the coast in Australia as well as from coastal Indonesia. These fish have bodies that are typically a silvery gray, but when they are fired up and ready to breed, they turn a brilliant dusty blue, with darker midnight blue bars running vertically along the length of the fish. However, this fish is best known for its fins. It has a rounded, fan shaped dorsal fin which is typically a yellow or red, or somewhere in between, with the fin rays being black, with varying density. The fish’s namesake, however, are in its other fins, the adipose and anal fins of the males specifically, which are the same color palette but have long, extended, thread-like filaments which they use both to spar with other rival males as well as to show off to prospective females. Their caudal and ventral fins also typically have extensions on them. When sparring, the males flash these open and closed rapidly, showing off not only the color that they can achieve, but their brilliant iridescence, flashing blue and silver.

These fish are typically found in freshwater swamps and lagoons, and slow-moving as well as seasonally dry streams and creeks. In these areas there is typically a lot of plants, growing densely on the edges of these habitats where the water is typically less than 4 feet deep. These rainbows can take a wide range of ph, temperature, and hardness, so you should not be too concerned about those things when setting up an aquarium for these fish. In the wild, the ph can shift from 5 all the way up to 8, and the hardness can go from undetectable all the way up to around 250 ppm. They are also capable of thriving in temperatures as low as 65, and as high as about 88! The main focus would be to keep them in clean water, which they will definitely appreciate, and so will you, when you see them swimming around each other in their battles.

These fish are very peaceful, and can be added to any peaceful community aquarium, although they will spar with each other, as well as with other dwarf rainbowfish if you keep them together. A community of Pseudomugil would be a great place to throw these guys into, so you can watch all of the males spar each other, whether they are the same species or not. These fish are capable of reaching a length of about 1¾ inches or so, and so you should keep tank mates that are a suitable size for them. Ours are currently 1¼ inches long, and you should see them get a bit bigger, but not an extreme amount. You might also consider keeping a species-only tank for these guys, since with nothing to disturb or distract them, you would most likely see the best behavior from them. These shoaling fish do not ship individually bagged.

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American-Bred Fish

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