Conservationists are thrilled after the discovery of a rare mudfish in the Auckland area.

Auckland Council along with staff from the Zoo, and Mahurangi Technical Institute teamed up to try and find new populations of the threatened black mudfish.

And they've struck gold in the Te Arai wetlands.

Council biodiversity advisor Matt Bloxham says they're now helping land owners protect them with planting and fencing along the edge of the wetland.

"Fish species like eels can traverse all sorts of different fresh water habitats but mudfish at least are totally tied to that wetland habitat."