New Zealand citizens planning to visit Fiji for a holiday do not need to apply for a visitor visa, as New Zealand is on the visa-waiver list. There are some exceptions to this rule, which are mainly to do with how long you want to stay.
If you have been sentenced to imprisonment, deported from any country, or have been involved in known criminal or terrorist groups, then you should contact the nearest High Commission or Consulate of Fiji well in advance of travel for advice on visa requirements.