freshwater community4


Threadfin Rainbowfish

threadfin rainbowfish

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Scientific Name:   Iriatherina werneri      
Min. Tank Size:   25 gallons   
Personality:   Peaceful      
Temperature:   75-86°F      
pH:   5.5-7.5/5-12°dGH      
Size:   2"      
Diet:   Omnivore      
Breeding:   Egglayer      


Other small Rainbowfish, small Tetras, Rasboras, Dwarf Cichlids, Corydoras and Otocinclus Catfish.

Threadfin Rainbowfish

When first introduced into the aquarium hobby in the 1970's, only males of the species were available. Today, however, both sexes of Threadfin Rainbowfish can be found. These fish exhibit dark coloration along their backs and males of the species may have a reddish tint on the dorsal fin and caudal lobes. Males of the species also develop thread-like extensions to the fins for which the fish is named. This species is also sometimes sold under the name Featherfin Rainbowfish. Threadfin Rainbowfish are native to Papua New Guinea, Indonesia and Australia where they can be found in slow-moving waters. These fish tend to inhabit streams, swamps and lagoons as well as drainage ditches. The favored habitats of these fish are densely vegetated.

Tank Set-up

In the home aquarium, Threadfin Rainbowfish prefer dim lighting, dense vegetation and gentle water flow. This species is very peaceful in nature and because it may be outcompeted for food by other species, it is not recommended for the community tank. If you decide to keep this fish in a community tank, choose tankmates wisely - no rowdy or boisterous types and definitely no fin-nippers!


The Threadfin Rainbowfish has a very small mouth and food should be crushed small enough to enable easy consumption. Flakes are easy to crush between your fingers to produce a small enough size. But, don't get lazy in your feeding regimen by providing only flakes. For optimum health and coloration, provide a varied diet of live and frozen foods consisting of bloodworms (freeze-dried can be crushed fairly easy), Daphnia, and brine shrimp.


Threadfin Rainbowfish can be bred in the home aquarium, but it does not spawn as easily as other Rainbowfish. This species is best spawned in a breeding tank with soft, acidic water decorated with plenty of fine-leaved plants. Because these fish may eat their own eggs, adults of the species should be removed from the breeding tank following spawning.

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