That's Bylxa japonica. Sadly it's not availible in NZ. It needs very high lighting, either T5HO's or metal halides, lots of ferts, softish water and a nutrient-rich acidic substrate.
Echinodorus tenellus tenellus is similar, although it doesn't grow quite as dense and it's leaves are more curved as opposed to Blyxa japonica, which has leaves that are quite straight.