http://nas.er.usgs.gov
For more information:
Nonindigenous Aquatic Species Database
amy_benson@usgs.gov
I know that there are many gaps in our data as we try to document the whereabouts of everything aquatic.  So if you know of species out of their range and would like to contribute that information so that I can continue to compile distribution information, please get in touch with me.  Thank you.