Didymo (Didymosphenia geminata) is an invasive freshwater algae which is present in some South Island rivers in New Zealand.

Didymo is most likely to be spread by humans moving items between waterways.

Changes to the cleaning method

In October 2021, The Ministry For Primary Industries (MPI) changed the recommendation about how best to clean your gear if you’re using dishwashing detergent.

Until then, the advice was to use a mix of 5% dishwashing detergent and water, and keep the item wet for at least a minute.

Now it's 10 for 10

The revised advice is to:

  • use a mix of 10% dishwashing detergent with water
  • leave the item wet for 10 minutes.

This is the first update for many years and the main reasons for it are changes in detergents and the pests that we need to stop.

This is based on research by NIWA, MPI will gradually update the Didymo resources with the "10 for 10" messaging.

What can Anglers do?

To ensure you don’t spread didymo, wherever possible restrict equipment, boats, clothing and other items for exclusive use in one waterway.

For more information on didymo read the MPI's latest info sheet about Didymo.

Also see our Felt Soled Waders Restrictions FAQ page for more important information on equipment restrictions.

You can read about the latest Didymo information by visiting the Didymo page on the MPI website.

Attention Fiordland Anglers: Any person wanting to fish on almost all of Fiordland’s rivers and lakes is required to obtain a Clean Gear Certificate for all gear. To read about this and other special conditions which apply to Fiordland National Park, click here.