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What does a pseudorasbora look like?
The pseudorasbora parva, also commonly known as the Asian gudgeon, is a small fish in the Cyprinidae family. It is native to East Asia (China, Japan, Korea...) and is best known as a disease vector. This is one of the reasons why it is considered a pest in Europe and France.
This silvery fish has a small head and mouth. It is slightly humped and has slightly compressed flanks. Its silhouette is slightly taller than that of a minnow, which has an almost cylindrical body.
It has relatively large scales for its size. It is very silvery with bluish to purplish and slightly golden highlights, with a dark steel-gray line along the lateral line.
Why is it harmful and how was it introduced?
Pseudorasbora parva is a nuisance because it is a healthy carrier of pathogens, the best-known of which is rosette disease. This disease is decimating a large proportion of native fish populations, notably the rotengle, one of the most sensitive fish to this disease and a true indicator of its presence.
Agent rosette is a half-animal, half-fungus pathogen that has no impact on pseudorasbora. It is transmitted by ingestion or simply via water to other species. It causes internal mycoses in fish, which can lead to death.
The Asian gudgeon has been introduced in several ways. In Europe, before it was associated with certain diseases, it was used as food for farmed carnivorous fish.
It was also used as an ornamental fish by some aquarists. It ended up in the wild, mostly as a result of deliberate introductions...
