New Zealand has maybe the strictest laws in the world when it comes to protecting the environment and native wildlife. Bringing seeds, honey or untreated wood into the country is a go straight to jail and do not collect $200 if you pass go kind of situation. With regards to the fish the Department of Conservation doesn't want Carp or any other invasive species introduced to the waterways. I suppose they learnt from the mistakes made in Australia with things like the Rabbit and Cane Toad. http://www.doc.govt.nz/nature/pests-and-threats/ https://panique.com.au/trishansoz/animals/australia-introduced-animals.html