Asian invader in the UK

This species is known by about 30 common names, mainly throughout Europe… and it’s not even a European species. In fact, its natural range embraces southern and eastern Japan, Taiwan, Korea, China and the Amur basin. However, it has been repeatedly introduced – either intentionally or accidentally – into more than 30 countries since 1960, hence the high number of common names.Among the countries into which the species has been introduced, no fewer than 26 report that they now have established populations, while most of the others believe that they have. Yet, since P. parva is not a particularly colourful fish and has never been particularly popular among fish keepers, why have there been such a high number of releases into the wild? And where have these releases originated?The fact is that while P. parva may not be particularly colourful, it is nonetheless quite attractively speckled all over, at least in adults. It has a largish eye, a dark line running from the head to the tail of its slim, streamlined body, and almost-black fins during the breeding season. It is an easy species to keep and breed and will spawn several times during the spring and summer months, laying up to 5 000 eggs. It is also – most unusually – capable of producing a clicking sound, which has given rise to one of its English names, clicking barb. However, it is not a barb; nor is it a rasbora (as may be implied by its scientific name).The prolific nature of the species is just one factor responsible for the mounting concern in the UK. Another is that it feeds on fish eggs. It also competes with other species for small invertebrates and has been seen to attack young fish and inflict wounds on larger fishes (it is believed to include fish skin and body tissues in its diet in the wild). Adding further to the fear surrounding its spread is its ability to carry at least two fish diseases. All these characteristics are obviously of considerable concern, not just to conservationists, but to ornamental and food fish farmers as well.I’m sure that it will come as no surprise to our readers to learn that the ornamental aquatic industry is being seen as one of the major offenders regarding releases. Precisely to what extent this is indeed the case is difficult to ascertain, but – as the fish used to be available for aquaria in the UK and still is in other countries – we cannot discount the possibility that at least some releases will have come directly or indirectly via our industry.Today…