They aren't illegal in Canada, Ontario (all species), Saskatchewan (as of 2011 or so) but thats it to the best of my knowledge. We are allowed all types in the Maritimes. I know British Columbia imports Argus for the Asian Live Food fish trade but I don't know where would be a good place to get one or if they would ship them. Don't get me wrong I care very greatly about the health of our natural environment, I would never release any pet into the wild ever even if it was something that I knew wouldn't survive our winters. With that said there are a ton of potential invasive species available at pet stores, plant nurseries ect., off the top of my head Norway Maple (class one invasive in many places), Koi, Goldfish, goutweed, Honeysuckle, Fanwort, Himalayan Balsam ect.The key is responsible ownership, of course with that said I would never keep any species that I am not permitted by law to do so. I have kept many different species of Snakehead in the past and I really want to try something new. I haven't tried Argus or the Blotched Snakehead so I am definitly interested in those two if there is any availability at all.