Giant Kōkopu
Only found in New Zealand, this nocturnal fish is classified as 'declining'.
Habitat: Wetlands, lakes, forest streams and lowland streams near the sea.
Nesting season: Autumn and winter with eggs hatching in spring.
Diet: Aquatic and terrestrial insects, freshwater crayfish, spiders and occasionally other fish.
Size: As the third largest freshwater fish species in New Zealand, giant kōkopu can grow up to 58cm (the length of 2 rugby balls) and 2.7kg (the weight of a brick).
What’s their superpower?
Giant kōkopu live in fresh and salt waters. After spawning in freshwater, their larvae are swept out to sea for about 5 months before returning to their home streams where they spend the rest of their lives.
Why do we need them?
Endemic to Aotearoa, they play a major role in keeping the aquatic ecosystem healthy and balanced. By snacking on aquatic and terrestrial insects, freshwater crayfish and spiders, they stop these critters from taking over. They’re also food for tuna (freshwater eels) and lots of marine fish species. Plus, they redistribute nutrients to the water through their waste which helps aquatic plants and algae continue to grow.
Did you know?
Scientists believe that adult giant kōkopu send out a special chemical signal that acts as a natural GPS, guiding their baby fish back to the safety of their home streams after being at sea.
Fascinating facts
Starry spots: Giant kōkopu have beautiful gold star-like spots, lines, crescent and rings on their bodies which inspired their species name: Galaxias (referring to galaxy).
Masters of hide and seek:
They love to hang out under logs, in shady pools and beneath overhanging plants, waiting to surprise their next meal.
Nighttime navigators: Giant kōkopu are nocturnal, meaning they are most active and do their feeding at night - it helps them avoid predators and catch unsuspecting prey.
Egg laying machines: Female giant kōkopu are expert egg layers, producing thousands at a time.
Smooth operators: They have no scales but a thick leathery skin covered with mucus that helps reduce friction and protect against infections and parasites.
Conservation corner
Sadly, giant kōkopu numbers are dropping across Aotearoa and are classified as threatened (the highest conservation status) in Tāmaki Makaurau. This is thanks to habitat loss, degradation and competition from introduced species, wetland drainage and land-use changes.
How you can help
Set traps beside streams in your area to keep pesky predators like rats, hedgehogs and mice in check.
Plant native vegetation along stream edges to create leafy shade which helps them thrive.
Protect streamside vegetation by fencing it off from farm animals.
Stop paint, sediment, chemicals, road run-off and rubbish from flowing into storm drains, as these can pollute streams.
Report sightings to the Auckland Council biodiversity team at biodiversity@aucklandcouncil.govt.nz
Help us to help the Giant Kōkopu
Giant kōkopu are found only in New Zealand. They lack scales and have a thick leathery skin covered with mucus. They are threatened and currently classified as 'declining'. Help the volunteer groups of the Waitākere Ranges restore their habitat.
With over 75% of our indigenous species at risk of extinction*, the Pest Free Waitākere Ranges Alliance is raising funds to help defend the many special species of the Waitākere Ranges.
Thank you for your support of this special fish!
Find out more
Image credits: Fern by Toby Hall on Unsplash • 25cm Galaxias Argenteus from Wainui Stream, Paekakariki, by Stella McQueen
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