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Rules & regulations

 See also...

Check, clean and dry to avoid spreading didymo



Anglers can help reduce the liklihood of didymo spreading by:

  • Always check, clean and dry equipment before using it again
  • Don't use the same equipment on different waterways without checking cleaning and drying
  • Using rubber-soled boots (felt-soled footwear is banned from 1 October 2008)
  • Bringing only clean fishing equipment into NZ
  • Being informed about didymo: see Didymo biosecurity alert
Check, clean and dry


Before you leave a river or lake, check items and leave debris at site. If you find any later, treat and put in rubbish. Do not wash down drains.


The Biosecurity New Zealand website advises that  there are several ways to kill didymo. Choose the most practical treatment for your situation which will not adversely affect your gear.

  • Non-absorbent items
    Detergent: Soak or spray all surfaces for at least one minute in 5% dishwashing detergent or nappy cleaner (two large cups or 500 mls with water added to make 10 litres); or

    Bleach: Soak or spray all surfaces for at least one minute in 2% household bleach (one small cup or 200 mls with water added to make 10 litres); or

    Hot water: Soak for at least one minute in very hot water kept above 60 °C (hotter than most tap water) or for at least 20 minutes in hot water kept above 45 °C (uncomfortable to touch).
  • Absorbent items
    Absorbent items require longer soaking times to allow thorough saturation.
    Hot water: soak for at least 40 minutes in hot water kept above 45 °C; OR
    Hot water plus detergent: soak for 30 minutes in hot water kept above 45 °C containing 5% dishwashing detergent or nappy cleaner; OR
    Freezing: Freezing until solid
  • Freezing
    Freezing any item until solid will also kill didymo.


Drying will kill didymo, but slightly moist didymo can survive for months. To ensure didymo cells are dead by drying, the item must be completely dry to the touch, inside and out, then left dry for at least another 48 hours before use.

Relying on ambient drying as a stand-alone treatment for decontaminating highly absorbent risk goods is not recommended in situations where use between waterways is frequent (daily, weekly or even monthly).

Drying should only be relied upon as a decontamination treatment if great care is taken to actively and completely dry the material (such as by using a heat source where temperatures around the felt are assured of reaching 30 °C). Once the material appears dry, complete dryness must be confirmed by a tactile inspection of the base of the fibres. Once completely dry, items must remain dry for at least 48 hours before use in another waterway.

Use rubber soled boots

A ban applies to using using felt-soled waders or footwear incorporating or having attached a sole of felted, matted or woven fibrous material when sports fishing.

Instead of felt-soled boots or waders, Fish & Game New Zealand recommend using rubber-soled alternatives that dry rapidly and are easily cleaned.


Replace your felt-soled boots

Banned felt-soled boots

Bringing fishing equipment into NZ

To slow the spread of the invasive alga didymo, in New Zealand waterways, MAF Biosecurity New Zealand requires all used freshwater fishing equipment brought into New Zealand to be clean and dry. Read more...

For more information

For more information about didymo, please see:



Scierra Dynatrack boots

Scierra Dynatrack boots


Light-weight Scierra Ipac wading boots



Didymo growth in the Hawea River, Central Otago.
Photo: Glenn Maclean, DOC


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