Fish migration is mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.
The Galaxiidae are a family of mostly small freshwater fish in the Southern Hemisphere. The majority live in Southern Australia or New Zealand, but some are found in South Africa, southern South America, Lord Howe Island, New Caledonia, and the Falkland Islands. One galaxiid species, the common galaxias, is probably the most widely naturally distributed freshwater fish in the Southern Hemisphere. They are coolwater species, found in temperate latitudes, with only one species known from subtropical habitats. Many specialise in living in cold, high-altitude upland rivers, streams, and lakes.
The common galaxias or inanga is a very widespread Southern Hemisphere fish in the family Galaxiidae. It is a slim, narrow fish with a forked tail and a mottled, spotty pattern, typically about 10 cm (4 in) long when fully grown. It lives in fresh water, but spawns at river mouths and spends the first six months of its life at sea, returning en masse in spring. Its vernacular names include cowfish, jollytail, common jollytail, eel gudgeon, inaka, native trout, pulangi, puye, slippery tarki, spotted minnow, Falklands minnow and whitebait.
The New Zealand smelt, also known as the New Zealand common smelt, New Zealand cucumber fish, or silveries is a smelt of the family Retropinnidae, found only in New Zealand at shallow depths in estuaries and rivers. Their length is between 8 and 13 cm.
The New Zealand longfin eel, also known as ōrea, is a species of freshwater eel that is endemic to New Zealand. It is the largest freshwater eel in New Zealand and the only endemic species – the other eels found in New Zealand are the native shortfin eel, also found in Australia, and the naturally introduced Australian longfin eel. Longfin eels are long-lived, migrating to the Pacific Ocean near Tonga to breed at the end of their lives. They are good climbers as juveniles and so are found in streams and lakes a long way inland. An important traditional food source for Māori, who name them ōrea, longfin eel numbers are declining and they are classified as endangered, but over one hundred tonnes are still commercially fished each year.
The shortjaw kōkopu is a galaxiid fish, endemic to New Zealand. They are large, scaleless fish which inhabit stable pools in cascading, bouldery streams with forest cover. Shortjaw kōkopu are amphidromous, with the fry going to sea after hatching, and returning as juveniles to fresh water where they grow to adulthood. They may grow to a maximum of 350 mm (14 in) in total length, but more commonly reach 150–200 mm (5.9–7.9 in).
The giant kōkopu is a threatened species of ray-finned fish in the genus Galaxias, found only in New Zealand. It can reach up to 58 cm (23 in) in length and 2.7 kg (6.0 lb) in weight, making it the largest species in the family Galaxiidae. It is a mainly lowland species, commonly found in slow-flowing streams, wetlands, lakes, and lagoons. Most populations have an amphidromous life cycle, with larvae going to sea soon after hatching and returning about four months later as small juveniles, 4.5–5 cm (1.8–2.0 in). Juvenile giant kōkopu form a small part of the annual whitebait catch.
Eldon's galaxias is an endangered galaxiid fish endemic to New Zealand. One of several fishes in the genus Galaxias found in Central Otago, it has a very small home range and is at risk of being driven to extinction by trout introduced for recreational fishing.
The torrentfish, or panoko (Māori), is an amphidromous freshwater fish that is endemic to New Zealand. Torrentfish are well adapted to life in shallow, fast-flowing riffles and rapids. They grow to a maximum of 20 cm (7.9 in) in total length, but more commonly reach 10–12 cm (3.9–4.7 in).
The New Zealand grayling is an extinct species of fish that was endemic to New Zealand. It was known to the Māori by many names, including pokororo, paneroro, kanae-kura, and most commonly, upokororo. The variety of names for the fish came from either multiple tribes, or to describe the fish at different periods of its life cycle. Even though this fish is named grayling, it is not related to European or American graylings and lacks the large dorsal fin ‘typical’ graylings are characterised by. It is, however, closely related to the Australian grayling. The New Zealand grayling was an amphidromous species, migrating between freshwater and saltwater during different seasons as well as stages in their life cycle. The last sighting of the New Zealand grayling was in 1923, and it was declared extinct in 2018.
The giant bully, tītarakura, or tīpokopoko (Māori), is a species of fish in the family Eleotridae endemic to New Zealand.
The common bully, or toitoi (Māori), is a fish endemic to New Zealand, and is present throughout the country. There are three other bully species that can be confused with common bullies. There are few characteristics of the common bully that separate it from other species. Vertical lines present on the cheek are a good defining characteristic, along with the location of head pores and scale patterns on the head although these are hard to establish when seen in the wild. It is an amphidromous fish meaning it is able to survive in marine and fresh water environments. It is a small fish only growing as big as 15 cm. It can live in marine, fresh water or brackish water habitats and generally lives in benthic zones. Some populations venture into the sea and occur in coastal rivers and streams while other land-locked populations have established in many shallow mainland lakes. They generally prefer moderate to slow moving water which means they are the most likely bully species to be sighted. Its diet consists mainly of small benthic invertebrates but also involves insect larvae and crustacea.
The upland bully is a species of fish in the family Eleotridae endemic to freshwater habitats in New Zealand. Both sexes have distinctive orange-brown dots all over the head. Adults generally reach a length of 8–10 cm (3.1–3.9 in).
The redfin bully is a species of freshwater fish in the family Eleotridae endemic to New Zealand. Being amphidromous, it spends part of its life cycle at sea. Males have distinctive bright red patterns and stripes on their fins. Adults grow to an average of 80–100 mm (3.1–3.9 in) total length, with a maximum of 120 mm (4.7 in).
Echyridella menziesii, the New Zealand freshwater mussel, also known by its Māori names kākahi, kāeo, and torewai, is a species of freshwater mussel endemic to New Zealand. E. menziesii is an aquatic bivalve mollusc in the family Unionidae, the river mussels.
The Indo-Pacific tarpon, also known as the oxeye herring or simply herring due to its superficial resemblance to the true herrings, of which it is not a member, is the smaller of the two species of tarpon and lives in Indo-Pacific waters.
Eleotris sandwicensis, the Sandwich Island sleeper, Hawaiian sleeper or oopu, is a species of fish in the family Eleotridae endemic to the Hawaiian Islands, where it can be found in marine, fresh, and brackish waters around the coast. Due to this capability of migrating between different marine environments, they are amphidromous. This fish can reach a length of 33 cm (13 in). It is locally important to commercial fisheries and is also used as bait by fishermen after larger fishes. In the Hawaiian language, the fish is also known as oʻopu, ʻoau, ʻowau, and hiʻu kole.
Sicyopterus lagocephalus, the red-tailed goby or blue stream goby, is a species of goby native to islands of the Indian Ocean from the Comoros to the Mascarene Islands to the Pacific Ocean where it reaches French Polynesia and can be found as far north as Japan. It is an amphidromous species: adults can be found in swift-flowing streams with rocky beds but the eggs hatch at sea and the larval stage remains in marine waters, migrating to freshwaters when they reach the postlarval stage. This species can reach a total length of 13 cm (5 in). In some places it is an important species for local consumption with the post-larvae being caught as they mass in estuaries.
Gerald Stokell was a New Zealand amateur ichthyologist.
Gobiomorphus is a genus of fishes in the family Eleotridae native to New Zealand and Australia. They are typically small, benthic fishes with large, rounded fins and two dorsal fins. Many have an amphidromous lifecycle: the eggs are laid in fresh water, but the fry are dispersed to sea soon after hatching, and grow there for several months before returning to fresh water.
