Oriental Weather Loaches are invasive fish species preferring lenticwaterbodies, such as backwaters, streams, swamps and periodicallyflooded pools and meadows. There are seven species described withinthis genus Misgurnus and several of them are increasingly spreading as invasive species across the globe. In 2019 a first observation of an Oriental Weather Loach was documented in a pond near Bocholt (Flanders), close to the Dutch border. In the Netherlands it was known that Oriental Weather Loach already occurred near the Belgian border in the Tungelroyse beek since 2012. However, besides this single observation in Flanders, it was expected that the species had not further invaded Belgium until then. A recent broad scale eDNA screening in that region carried out at 50 locations in 2019 and 20 20 unfortunately revealed that the species already colonized a large number of streams, ditches and ponds over relative large distances (> 10 km) from the Dutch border. Barcoding additionally revealed that this new species is Misgurnus bipartitus instead of M. anguillicaudatus as it was previously incorrectly identified and thought to be. At seven locations the species co-occurred with the native and Habitat directive species M. fossilis, which poses serious concerns regarding the problem of hybridization. The obtained results are discussed in this article and again confirm that eDNA monitoring is valid addition to traditional monitoring methodsto detect and monitor both invasive and rare freshwater fishes.
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