New Zealand status: Native
Conservation status: Declining
International conservation status: Vulnerable (IUCN)
Found in: New Zealand’s North, South, Stewart Island/Rakiura, Chatham Island/Rēkohu/ Wharekauri.
Threats: Sedimentation, introduced fish, habitat disturbance and removal of stream-side vegetation.
Appearance and size
Giant kōkopu (Galaxias argenteus) grow to 200–300 mm long, and can reach 400 mm. In 1899, one giant kōkopu was recorded at 580 mm long and 2.7 kg, but fish of that size are uncommon today.
Larger fish are covered with distinctive golden patterns and spots. These patterns led to the ‘galaxiid’ name being given to this family of fish because they look like a galaxy of stars.
Giant kōkopu can live for more than 20 years.
Where they live
Giant kōkopu are usually found in wetlands, lakes and forest streams close to the sea. They are unable to climb large obstacles like waterfalls, which stops them moving further inland.
Giant kōkopu usually live where there is some cover over the water, like overhanging branches, riverbanks, logs or debris. They dart out from these hiding places to catch prey like kōura, spiders and cicadas.
Giant kōkopu are also found in lakes and rivers that don’t connect to the sea. These include three small lakes near Te Anau – Mistletoe, George and Luxmore.
Lifecycle
Giant kōkopu are one of the five species of migratory galaxiid found in Aotearoa. Migratory galaxiids move between streams, rivers and the sea during their lifecycle. They are one of the six species caught as whitebait when juvenile fish enter rivers and streams to begin their upstream migration.
Inanga lifecycle
Image: DOC