I speak of the exotic zoonotic disease piscine tuberculosis which has been transmitted from fish in quarantine to people working in the facility on a number of occasions in NZ. There have also been outbreaks of whirling diseease in trout hatcheries and who would know where it originates from.
I think you are missing the point a bit. There are many diseases which are not normally found in NZ and the reason they are not is because of the precautions taken at our borders. For instance we have managed to avoid the plague because we do not have rat fleas here and we try to make sure rats are kept out by keeping foreign ships free of rats. This is the purpose of quarantine, not to respond after there has been a massive outbreak of disease. The same applies to diseases of fish.