Aliens just a click away: the online aquarium trade in Italy

The aquarium trade moves thousands of species around the globe, opening the door to unwanted organisms being released into fresh and marine waters, with subsequent adverse ecological and economic impacts. Unlike ballast waters, the commerce of ornamental pets and the aquarium trade have only recently been recognized as major pathways for the introduction of fish, invertebrates and plants, with online commerce in particular being a thriving business. Here, we report the results of the first study on the online aquarium trade in Italy. We examined 54 online aquarium shops and collected data about the animals and plants sold. For each species, information about its native range, reproduction, feeding habits, pathways, impacts, status in Italy and price were gathered, in order to identify previously recorded or potentially invasive species for Italy. Freshwater fish and plants represent the most sold taxa, and mainly come from the Americas. Most animals are omnivorous, and the plants can reproduce through both reproduction modalities (asexual/sexual). Half of the traded plants have already been introduced outside their native range; however, the majority of the species sold have not yet been recorded in the wild in Italy. As expected, a high percentage of the sold species are reportedly introduced due to escape/release for ornamental purposes. Data on their impact is scanty and mainly concerns the already known invasive species and their ecological damage. Although the multilevel impact exerted by invasive species is recognized worldwide, in Italy the average price of invaders is quite low, thus favoring their purchase. In addition, considering the nation's growing number of aquarists, the probability of releasing potentially invasive species through the online trade is very high: more information, accurately presented information for buyers and stakeholders, and appropriate regulations may change this trade in order to reduce the risk of new invasions.