Bostockia porosa is a species of fish in the family Percichthyidae, the temperate perches. It is known by the common name nightfish. It is endemic to Australia, where it occurs in lakes, ponds, swamps, rivers and streams. It prefers areas with rocks, vegetation or debris to use as cover and is active during the night. This species grows to a length of 15 centimetres (5.9 in) SL though most are only about 9 centimetres (3.5 in). This species is the only known member of the monotypic genus Bostockia.