New Zealand's Galaxiids
Updated: May 29, 2020
New Zealand has many unique and endemic species from birds to reptiles. But how about our overlooked freshwater fish species: galaxiids! They boast a plethora of cool adaptations from scaling rock walls to head sensors.
New Zealand has five species of migratory galaxiids, three of which are unique to New Zealand . The name galaxiid refers to the pattern on the skin of adult fish which looks like a galaxy of stars . Galaxiids have an interesting life cycle, where they spawn in the ocean and migrate into freshwater rivers and streams to live as adults .
Inanga (Galaxias maculatus)
Inanga are New Zealand’s most commonly caught fish . They are found in a range of habitats from wetlands and lakes to small creeks, but are poor climbers so they stay close to the coast . Inanga have the widest distribution of any native freshwater fish, found in Chile, Australia and Argentina . Their silver belly and slightly forked tail make them easy to distinguish .
Banded kokopu (Galaxias fasciatus)
Banded kokopu is endemic to New Zealand, nicknamed Maori or native trout . They are good climbers, and can be found up to 550m above sea level in pools with logs and boulders . A cool thing about all galaxiid species is that they have a sensor on their heads to detect when something hits the water, such as insects that fall from overhanging plants . Their tell-tale feature is the pale vertical stripes across their sides .
Giant kokopu (Galaxias argenteus)
The giant kokopu is the largest galaxiid species in the world but is also only found in New Zealand . One individual measured 580mm and weighed 2.8kg!  They also have long lifespans, living up to 20 years . Like inanga, giant kokopu aren’t great climbers and are generally found close to sea, inhabiting wetlands, lakes and forest streams . Giant kokopu rely on bushy surroundings for disguise while stalking their prey before quickly catching it .
Koaro (Galaxias brevipinnis)
Koaro are solitary fish, reaching an average of 180mm in length with skin that shines with iridescence . Koaro are adept climbers with the ability to scale near-vertical waterfalls by using specially formed broad fins that have a grippy texture underneath . Koaro are the most travelled galaxiid species, being found as far as 400km inland and as high as 1300m above sea level!  They prefer the fast-flowing, cool, tussock or forest streams . Unfortunately, koara have been classified as ‘in decline' .
Shortjaw kokopu (Galaxias postvectis)
Shortjaw kokopu, the third endemic galaxiid species in New Zealand, are rarely seen and are classified as ‘threatened’ . This is likely due to the fact that they can only exist in a narrow range of habit, including boundary forest streams at low to moderate elevations, most of which have been degraded by intensive forest clearance . They are easily distinguished by their undercut jaw, which is used to scrape aquatic insects from rocks .
Galaxiids are best known in New Zealand for their contribution to the collective term ‘whitebait’. Whitebait are juveniles of six fish species, five of which are galaxiids . The sixth species is common smelt. Galaxiids are greatly overlooked as some of New Zealand’s endemic species but play an important role in our freshwater ecosystems. Whitebait fishing most commonly uses large open-mouthed hand-held scoop nets to catch juveniles as they migrate back into freshwater . This drastically reduces the number of individuals that live to maturity and breed. Regulations are already in place to restrict white-baiting to a seasonal activity  and are targeted at catching the common inanga while avoiding the less common species that migrate to either side of inanga. However, these four other galaxiid species still face ‘threatened’ statuses [4,5].
While managing and maintaining the status of galaxiid species relies on the strict management of the whitebait industry, direct fishing of juveniles is not the only threat they are facing. The degradation of waterways through forest clearance, agriculture and urbanisation have increased the decline of galaxiid species [6,7]. For inanga in particular, which rely on dense riparian vegetation lining the edges of waterways and shade cover [7,8], the loss of suitable spawning habitat has been doubly worrying. As inanga numbers reduce, not only do chances increase of white-baiter’s catching endangered galaxiid species, but juvenile inanga remains an important marine food source for many species including herring, sardines, mackerel and sprat . To improve whitebait management, DOC delivered a new proposal in early 2020 to “ensure healthy and restored white-bait populations’. Protecting our unique freshwater ecosystems, including supporting these proposed regulations, will play a huge role in the recovery of galaxiid species that are just as endemic, rare and unique as some of our native birds.
If you’re interested in doing more, take a look at these links:
 Richardson, J.; Taylor, M.J. (2002). A guide to restoring inanga habitat. NIWA Science and Technology Series No. 50 (PDF). Wellington: NIWA. ISBN 978-0-478-23255-4.
 Hickford, Michael; Schiel, David (2011). "Synergistic interactions within disturbed habitats between temperature, relative humidity and UVB radiation on egg survival in a diadromous fish". PLoS ONE. 6 (9): e24318. doi:10.1371/journal.pone.0024318
Lena is studying an honours degree at AUT. Her research is comparing behavioural differences of Nemo fish in captivity and the wild. As a part time job, she teaches at the university. One of her favourite pastimes is to banter about current environmental issues. However, this tends to be only with people who agree, so it’s generally one-sided.