hunts in the lowland lake shallows

Size
Length: 30–40 cm, Weight: 0.5–1.5 kg
Lifespan
10–15 years
Diet
Feeds on small fish aquatic insects and crustaceans. Also consumes worms and occasionally baby ducklings. Hunts actively at night in shallow waters after hiding during day.
Habitat
Inhabits large deep lakes and slow meandering stretches of lowland rivers. Hides under overhanging banks logs and deep pools during day. Comes out to hunt in shallows at night.
Range
Found in North Island particularly in lowland lakes and rivers from Northland to Wellington. Most common in large deep lakes and slow meandering lowland rivers with suitable cover.
Endemism
Endemic
Main Threats
Habitat loss from wetland drainage and stream modification is primary threat. Water pollution and sedimentation also impact populations. Predation by introduced trout and perch significant.
Population
At Risk - Declining. Once common in lakes and rivers of North Island. Populations hammered by drainage of wetlands pollution and predation by introduced trout and perch.
Conservation Status
At Risk - Declining
Human Risk
harmless
Handling Note
protected native freshwater fish do not disturb in habitat
Conservation Note
Endemic freshwater fish; declining due to habitat loss, barriers to migration, and introduced predators.
Assessment
NZTCS Freshwater Fishes (2023)
Te Ao Māori
In Māori tradition the large native galaxiids were known as kokopu. The name refers to their habit of lurking in deep holes. They were an important food source for inland tribes. Caught at night using torches and nets they provided sustenance. Today they are the ghost fish of our lowland streams. They are the monster that local kids swear they saw under the bridge. No one ever seems to catch them.
The largest member of the whitebait family. This is a fish that starts tiny and ends huge. Giant kokopu grow into absolute units. They reach over 40 centimetres in length and weigh more than a kilogram. In the native fish world they are the equivalent of brown trout. The body is mottled olive-green and gold covered in irregular dark blotches and speckles. It provides perfect camouflage against the dappled light of a forest pool. The fish hides in plain sight. Ambush predators with a serious lazy streak define this species. During the day they hide under logs or in deep dark holes. They barely move. At night they transform into active hunters. They roam the shallows and gulp down insects worms small crayfish and even baby ducklings if they can catch them. The mouth is huge. It extends back past the eyes. It is designed to open wide and create a vacuum that sucks in anything that fits. The fish eats whatever fits. A tragic navigation problem plagues their existence. Giant kokopu are migratory just like their whitebait cousins. The babies hatch in fresh water. They float down to the sea to grow. Then they try to swim back up the rivers as adults. But they are terrible climbers. If a culvert is too high or a dam blocks the way they just give up. They die downstream. It is a fish that cannot go home. To see a giant kokopu is to see a relic. It is a big beautiful lazy predator that is slowly being locked out of its own home. These are the ghost fish of the lowland streams. The pool is dark. The kokopu hides under a log waiting for night. The culvert upstream is too high. The fish cannot pass. It does not know why. It just knows it cannot go home. So it waits. That is all it can do. The silence in the pool is heavy. The fish is there. But the river is broken. And the journey is over before it begins.