I know there are plenty in Oz. I would assume that there would be a few around in NZ too.
Acanthicus adonis, Polka-dot lyer tail could be it, if not the hystrix. I had a polk dot a few years ago, one very very angry little guy, had to get rid of it! A mate took it off my hands and it tore his L25 to pieces, the scarlet was twice his size too.
Would love to know where you saw it...Must have been in one huge tank...