only found far inland if the gradient is low and there are no barriers. Life Cycle Torrentfish are amphidromous: the fry go to sea after hatching, and return as juveniles to fresh water where they grow to adulthood. Female torrentfish are found further upstream than males, up to 235 km from the sea, with a large area of overlap. Females migrate downstream over summer and autumn when ready to lay eggs, and return upstream once spent. It is likely that they spawn in the lower reaches of waterways. Fry hatch and migrate to sea in late summer and autumn, returning a short time later in late autumn and winter. Because they have to spend time at sea, torrentfish are unable to form landlocked populations like some other New Zealand native fishes. Biogeography The torrentfish is related to the blue cod, an obligate marine fish, and is one of only two New Zealand freshwater fish with local marine origins. All of the other New Zealand freshwater species have Australian freshwater ancestors which arrived in New Zealand via dispersal through the sea. The torrentfish is the only member of both its genus and its family. Conservation In 2014 the New Zealand Department of Conservation classified the torrentfish as "At Risk: Declining" with the qualifier "C – very large population and low to high ongoing or predicted decline". Also in 2014 the IUCN rated the torrentfish as "Vulnerable". Torrentfish require a specialised habitat with cool, highly oxygenated, fast-flowing water, and so are threatened by water being taken for irrigation, water pollution, and climate change. River sedimentation is also a threat, as torrentfish need to live amongst loose gravels and are less common in waterways with compacted substrate. References External links Torrentfish discussed on RNZ Critter of the Week, 10 March 2017 Trachiniformes Endemic freshwater fish of New Zealand Fish described in 1874 Taxa named by Julius von Haast