New Zealand Freshwater Fish
Scroll through the species below or click on the link to go directly to a specific animal.
Names: Cockabully / Toi toi.
Habitats: Saltwater and brackish water.
Size: Up to 15cm.
Feed: Insect larvae.
Special Features: Excellent camouflage and can live in swift moving streams.
A familiar sight in New Zealand rock pools, the Cockabully is a brackish water (water that's more salty than freshwater) fish and can be found several kilometres up stream from many of New Zealand's tidal estuaries and rocky coastlines.
Names: Freshwater Crayfish (Paranephrops) / Kōura.
Habitats: Common in most well oxygenated freshwater environments in New Zealand.
Size: 70-80mm across fully grown.
Feed: Seabed scavengers.
Special Features: Has pincers like a lobster.
Found in most freshwater environments in New Zealand, Kōura use their four pairs of walking legs to get around and when alarmed, can flick their tail forwards violently to propel themselves backwards at speed in order to avoid any threat.
The Kōura is dark green and mottled like the stones it lives amongst on stream bottoms, giving it great camouflage. Often its waving feelers and black beady eyes are all that can be seen, as they stay hidden during the day, moving around mostly at night. Their front legs are used for scavenging food and warding off predators.
The Northern Kāura are found mainly in the North Island, but also in Marlborough, Nelson and the West Coast of the South Island – they reach lengths of about 70mm. Southern Kāura are found only in the east and south of the South Island, and on Stewart Island – they reach lengths of about 80mm.
Names: Freshwater Mussel (Echyridella menziesi) / Kakahi.
Habitats: Freshwaters in some parts of New Zealand.
Feed: Filter feeder, which feeds on algae blooms and plankton.
Special Features: Larvae live on freshwater fish for 1-2 weeks before hatching.
A protected species, Freshwater Mussels are similar in size to saltwater mussels but their shells are thinner. Their larvae are parasitic on fish for a week or two of their life cycle, but this does not seem harmful to the host fish.
Formerly common in lakes and streams around New Zealand, the Freshwater Mussel was an important food source for Māori. But like many freshwater mussels worldwide, they're now endangered by pollution and the introduction of new species of fish.
Names: Longfin Eel (Anguilla dieffenbachii).
Habitats: Mature in freshwaters before migrating to breed in saltwater between New Zealand and Tonga.
Size: After 20 years of age (and migration), 60cm-1.5m.
Feed: Omnivores – largely consists of insect larvae but when mature also feed on small saltwater fish and trout.
Special Features: All our eels have been known to nibble children's fingers ... so keep well away!
The Longfin Eel at the National Aquarium is called 'Big Mama'. She's been here since 1990, when a commercial eeler caught her in a farmer's dam. Big Mama has become quite tame, and is able to be patted and hand-fed by the divers.
The New Zealand Longfin Eel is New Zealand's only native freshwater eel and like some other eels, Longfin Eels have an unusual migration system where they grow and mature into fertile adults in freshwater systems then migrate to the sea to breed. New Zealand Longfin Eels have been known to live until 106 years old and weigh up to 24kg. True.
Longfin Eels breed only once at the end of their life, making the journey of thousands of kilometres from New Zealand, migrating to their spawning grounds in Tonga. Mature eels (male and female) subsequently die following breeding, with their eggs floating to the surface and hatching into flat leaf-like larvae that then drift along large ocean currents back to New Zealand, taking up to 15 months to arrive.
Upon arrival back in New Zealand these larvae metamorphosise into glass eels, which resemble small transparent adult eels. These glass eels occupy estuaries where they develop colouration and become elvers, before migrating upstream where they develop into adults eels.
Names: Shortfin Eel (Anguilla australis schmidtii)
Habitats: Freshwaters throughout New Zealand.
Size: Up to 1m and 3kg.
Feed: Insects, fish and just about anything else!
Special Features: Young eels can climb waterfalls and wriggle over ground from isolated waterholes or lakes to rivers.
The Shortfin Eel is native to the freshwaters of southeast Australia, New Zealand, and much of the South Pacific. Its body is long and snakelike, roughly tubular with a small head and jaws reaching back to below the eye or even further.
Their colour varies from a deep olive-green to a light gold or sometimes even yellow. They have no patterned markings but their underside is pale, often silvery, and the fins greenish. They grow quickly and in mature stages, migrate back to sea to spawn.
Names: Whitebait (Galaxius maculates).
Habitats: Freshwater (temporarily saltwater).
Size: 25-50mm long.
Feed: Start life at sea as part of plankton chain feeding on it. Return to estuaries and streams to eat insects and larvae.
Special Features: There are five different species of Whitebait in New Zealand.
Most commonly known as a delicious delicacy, Whitebait is made up of five species of fish and can grow up to be native New Zealand freshwater species such as Inanga, Banded Kokopu, Koaro, Shortjaw Kokopu and Giant Kokopu.
Whitebait is the collective term for a 'fry' of fish, true story. As young fish travel together in schools along New Zealand's coastlines, they then move into estuaries and sometimes up rivers to mature where they're often caught with fine meshed fishing nets. The most common grow into Giant Kokopu, on display at the National Aqaurium.
New Zealand Whitebait are the juveniles of freshwater fish, which mature and live as adults in rivers in native forests. The eggs of these fish are swept down to the ocean in autumn and form part of the ocean's plankton mass where they hatch. Approximately six months later in spring they return to rivers and move upstream to live in freshwater.