Marmorkrebs (Procambarus fallax f. virginalis) are the most popular crayfish in the North American pet trade

Introductions of non-native crayfish around the world are increasingly tied to the distribution, sale, and eventual release of pet crayfish. As part of risk assessment for the introduction of non-native crayfish in North America, I monitored the sale of crayfish on an auction website that specializes in aquatic pets and aquarium supplies for a year. Three species accounted for the majority of sales: the parthenogenetic crayfish, Marmorkrebs (Procambarus fallax f. virginalis), the Cajun dwarf crayfish (Cambarellus shufeldtii), and the orange morph of the endangered Mexican dwarf crayfish (Cambarellus patzcuarensis). Almost half of individual crayfish sold (48.5%) were Marmorkrebs, which is more than twice as many as C. shufeldtii, the second most commonly sold species. The Louisiana red swamp crayfish (Procambarus clarkii) was often offered for auction, but was bought much less often than the other three species. About 11% of P. clarkii auctions were successful, while more than 45% of auctions were successful for the other three. Four Cherax species were the only crayfish sold online whose native range was outside North America. Neither Marmorkrebs nor the orange morph of C. patzcuarensis can be collected regularly from natural habitats in North America, suggesting that most crayfish sold online in North America are obtained from existing stocks in the pet trade, rather than being collected from natural habitats.