The common river galaxias or Canterbury galaxias (Galaxias vulgaris) is a galaxiid fish of the genus Galaxias, found only in Canterbury, New Zealand. Description Galaxias vulgaris are a small freshwater fish which usually grow to 100–115 mm in length. They have a large mouth with a somewhat undercut lower jaw, pinched nostrils and a rounded snout. The fins are thick and fleshy. The pectoral fins are low and downturned. The caudal peduncle long and slender, the length of which is about 1.5 times the depth. They are a speckled brown/grey/olive to match the gravel substrate in which they live and have highly variable black banding or blotching along their back. This pigmentation is so effective as a camouflage, that it allows them to move out from the sanctuary under the rocks and spend time in the more open river in relative safety. They are easily confused with koaro which are slightly angled towards each other, but the eyes of G. vulgaris are larger and angled towards each other so the eyes are more visible when viewed from above. Galaxias vulgaris can be further distinguished from other Galaxid species by its less dense mottled pigmentations, a slightly larger and wider body than other species. Distribution Galaxias vulgaris are found in rivers and streams throughout the Canterbury South Island (with the exception of Banks Peninsula and in eastern Otago. The distribution ranges from low to high elevations in the shallow waters of rivers and streams. It is no longer found in many of the main river systems due to predation from introduced trout species Oncorhynchus mykiss (rainbow trout), and Salmo trutta (brown trout). Habitat preferences Preferred habitat of Galaxias vulgaris is fast flowing sections of stream which are well aerated and with open tussock grassland. Here, they inhabit the areas between and under rocks during the day and venture out into the more open areas of water to feed in the evening and night as Galaxias vulgaris generalized is solitary, nocturnal and largely cryptic invertebrate predator. Due to introduced trout, they are often excluded from the main base of rivers, or smaller over crowded rivers, but they can be found in side braids and tributaries. As Galaxais vulgaris is a non-migratory fish, populations are confined to the river systems in which they are born. As they do not enter marine environments they become isolated from populations in other water systems. Often, the