Galaxias maculatus

The common galaxias (Galaxias maculatus) or inanga (from the Māori īnanga) is a very widespread Southern Hemisphere fish in the family Galaxiidae. It is 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, slippery tarki, spotted minnow and whitebait. Common galaxias have iridescent silver eyes, undersides, and gill covers, and some have an iridescent green stripe along the top of their bodies which can be intermittently seen as they swim. Their specific name maculatus ('spotted') comes from the pattern of dark-mottled, leopard-like spots on an olive-brown background along their upper bodies. This pattern ranges from very subtle to quite bold. Common galaxias have slightly forked tails, unlike other most other galaxiids, which have square tails. Adults typically range from 8–11 cm (3.1–4.3 in) in length, with an average of 10 cm (4 in). The maximum reported length 19 cm (7.5 in). They are commonly found in small schools or shoals in slow-moving water, but can be more solitary in swifter streams. Common galaxias are one of the most widely distributed freshwater fish in the world. They inhabit Chile (35–55°S), Patagonia, Argentina, the Falkland Islands, some Pacific Islands such as New Caledonia, New Zealand, and coastal streams in southeastern Australia, Tasmania, and southwest Western Australia. Adults are mainly found in still or slow-moving water in the lower parts of coastal streams and rivers, or around the edges of lagoons; they can tolerate a wide range of natural conditions. If oxygen levels are low as a result of eutrophication, they can jump out of the water (emerse) and take up oxygen through their skin as a last resort. They need access to riparian vegetation for spawning, and usually live in river systems with access to the sea, as their larval stage is marine. They tend to be found in lower-elevation streams as unlike other species of Galaxias they cannot climb past waterfalls. Common galaxias can become land-locked (such as in five lakes in Northland, New Zealand), feeding and breeding in large beds of reeds. This species is usually considered amphidromous, a particular type of diadromy meaning that reproduction occurs in fresh water and larval growth occurs in the sea. Adult fish typically reach sexual maturity at one year and spawning is triggered by changes in day length and temperature. Unless landlocked within a lake, the common galaxias spawns mainly in autumn during spring tides in the tidally influenced reaches of rivers and streams but spawning in winter and spring has occurred. The eggs are laid en masse amongst flooded riparian vegetation by females. Male fish then release sperm into the water and the eggs are fertilised externally.