Aquarist is a hobby that involves raising fishes, invertebrates and aquatic plants in a domestic aquarium or in a garden pond. The animal and plant species used in this activity are, for the majority, of exotic origin and almost the 80% of ornamental import fishes comes from the South-east Asia and from the Japan. Without the appropriate attention, the aquarist could represent a way of voluntary or accidental entrance of many alien species in the natural environment and it is therefore necessary to inform both the possible buyers, helping the choice of non-invasive species, and those who already own specimens of invasive alien species promoting a responsible behaviour.