Pinchy Business: Poland's Ornamental Crayfish Trade in 2024

The aquarium trade is one of the main pathways for the introduction of non-native freshwater species. Such species include crayfish, which are valued ornamental animals commonly kept in aquaria. Some crayfish have been released into the environment, becoming invasive alien species. Due to the threat they pose to biodiversity and related ecosystem services, they have been subject to legal restrictions as invasive alien species of Union concern. In Poland, examples of species that have entered aquatic ecosystems this way include red swamp crayfish Procambarus clarkii and the marbled crayfish Procambarus virginalis. Given the highly developed aquarium pet trade in Poland, a detailed analysis of the availability of crayfish in the pet trade was conducted. This study examines the presence and sale of crayfish at locations at zoological trade fairs, shops, and online marketplaces in Poland. Additionally, pricing, the volume of imported crayfish, and their welfare in the year 2024 are presented. Crayfish were recorded in all surveyed locations. In shops and zoological trade fairs, five crayfish species were recorded, including the invasive alien species P. clarkii and C. destructor. Online advertising platforms featured 15 crayfish species, of which four were invasive alien species. Cambarellus patcuarensis was the most commonly sold species in all examined places. Crayfish were often kept in poor condition. Furthermore, many sellers probably disguised the species of crayfish being sold illegally. This work shows that trade in invasive alien crayfish species is still widespread in Poland.