The popularity of freshwater crayfi sh (Crustacea: Decapoda: Astacida) as ornamental pets has mainly increased in the last two decades (Pekny 2003, Lukhaup and Pekny 2009, Chucholl 2013a). Approximately one fi fth of the global crayfi sh species diversity has been recently moved between continents and countries for this purpose, including endangered species as well as potentially invasive species (Chucholl 2013a). Some of the ornamental crayfi sh species have been deliberately released from aquaria into nature or escaped from garden ponds and eventually became invasive in their new range (Jones et al. 2009, Chucholl et al. 2012).