Mudfish are becoming increasingly threatened by habitat loss, invading pest fish and reduced water quality. This brochure focuses on black mudfish in the Waikato and explains how mudfish can live on land and some simple ways to help save them from decline.
Summary
Like other mudfish species, black mudfish have a number of very unusual adaptations for the wetlands and peat lakes in which they live. They can survive out of water and breathe oxygen for several months when their wetland habitat dries out over summer, as long as they are kept moist by burrowing under tree roots or into mud or damp leaf litter. Black mudfish can slow down their heart rate and the amount of energy they need to live (similar to hibernating bears but called aestivation in mudfish), but immediately wriggle into life when water returns. Their skin is coated in tear-like mucus, which helps keep them moist out of water and also protects the fish against infection. They can even breathe air through their skin.
Despite these clever adaptations, black mudfish have very specific habitat requirements, more so than other species of mudfish and are particularly vulnerable to habitat loss, pest fish and water quality decline.
What you can do to help
Here are some things to do to keep mudfish in the Waikato:
- Fence stock out of waterways.
- Plant harakeke/flax and native sedges like carex and toetoe (not pampas) along stream banks and drains. Vegetation rooted in shallow water in and around farm drains helps provide black mudfish with shelter and food and reduces the water temperature, retaining moisture which is essential for mudfish survival.
- Clear farms drains less frequently, retaining vegetation to provide habitat and shade. Use a digger-arm to protect drain-side vegetation.
- Protect wetlands on your property. As well as being mudfish habitat, wetlands filter farm run-off and help keep the streams clean.
- Create a farm management plan that includes nutrient budgeting, effluent disposal and sustainable peatland management. You can get help with creating farm management plans from the Waikato Regional Council, DairyNZ and NZ Landcare Trust
- Read NZ Landcare Trust's fish factsheet 'Native fish on the farm' at www.landcare.org.nz.