Siamese Algae-eater Influenza-like Virus

The Siamese algae-eater (Crossocheilus oblongus) is a species of freshwater fish in the family of carps (Cyprinidae). It is a bottom-dwelling tropical fish that is found in river basins of mainland Southeast Asia, including that of the Chao Phraya River and Mekong River basins, as well as the Malay Peninsula.

Its natural habitats are streams and rivers as well as flooded forests during the rainy season.

The Siamese algae-eater can grow up to 15 centimetres in length and become as old as 10 years. They have a black horizontal stripe extending from nose to end of tail. The stripe can quickly fade to camouflage the fish against its surroundings, which is observed during fights or stress.

They are valued in the aquarium trade for being the only known fish species to consume red algae.

But the Siamese algae-eater is also host to an unexpected guest: the Siamese algae-eater influenza-like virus which scientist identified and reported in 2020[1]. While there are limited meta-data available, the library was prepared from gill tissues. There was no evidence of this virus in any other Siamese algae-eater samples available on the Sequence Read Archive (SRA).

For the Siamese algae eater influenza-like virus all eight segments with genome arrangements similar to that of Influenza A Virus and Influenza B Virus were identified.

The data generated in this study strongly suggest that influenza-like viruses can infect diverse classes of vertebrates and that influenza viruses have been associated with vertebrates for perhaps their entire evolutionary history.

[1] Parry et al: Divergent Influenza-Like Viruses of Amphibians and Fish Support an Ancient Evolutionary Association in Viruses – 2020.