The nightfish (''Bostockia porosa'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

, a

temperate perch Percichthyidae, the temperate perches, are a family of freshwater ray-finned fish found in Australia and southern South America. Formerly placed in the order Perciformes, they are now placed in the order Centrarchiformes. The name Percichthyida ...

from the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Percichthyidae which is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

southwestern Australia Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna. The region is also known as the Southwest Au ...

Taxonomy

The nightfish was first formally described in 1873 by the French

naturalist Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...

François-Louis Laporte, comte de Castelnau François-Louis Nompar de Caumont Laporte, comte de Castelnau (born ''François-Louis Nompar de Caumont La Force''; 24 December 1802 – 4 February 1880) was a French natural history, naturalist, also known as François Laporte or Francis de Caste ...

. The type locality was given as the Cygnes River in the interior of

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

. Castelnau also described the new

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus ''Bostockia'' for this new species. The is genus is

classified Classified may refer to: General *Classified information, material that a government body deems to be sensitive *Classified advertising or "classifieds" Music *Classified (rapper) (born 1977), Canadian rapper * The Classified, a 1980s American ro ...

within the family Percichthyidae, the temperate perches. The genus name honours the

Anglican Anglicanism, also known as Episcopalianism in some countries, is a Western Christianity, Western Christian tradition which developed from the practices, liturgy, and identity of the Church of England following the English Reformation, in the ...

minister Rev. George James Bostock (1833-1881), a collector of fish specimens for Castelnau in Western Australia, he collected the nightfish type. The specific name ''porosus'' means “holed” or “pored”, an allusion to the pores around the head.

Description

The nightfish has an oblong and compressed body with a large, oblique mouth which has a slightly protruding lower jaw and which reached beyond the rear edge of the pupil. Both jaws and the roof of the mouth have bands of villiform teeth. It has an incomplete

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

which has 43-47 tubed scales. There are large obvious open pores around each eye and along the upper part of head and along the jaws. The gill cover ends in a double spine. The

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

contains 7 or 8 spines, spines 3 and 4 being the longest, and 16-17 soft rays, the spiny and soft-rated parts separated by a deep notch. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

has 3 spines and 11-12 soft rays. The anal and

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

s are rounded. It is normally deep olive purple to black or dark-brown but can be light-brown with a dark brown mottling when living in lighter environments. The maximum recorded

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

is , although most fish are around .

Distribution

The nightfish is endemic to the coastal wetlands of

Southwest Australia Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna. The region is also known as the Southwest Au ...

. It is common and is found between the Hill River, near Jurien Bay and the

Kalgan River The Kalgan River is a river in the Great Southern (Western Australia), Great Southern region of Western Australia. Geography The river is long and, along with the King River (Western Australia), King River, drains into Oyster Harbour. The l ...

near Albany.

Habitat and biology

The nightfish is found in coastal streams, lakes and ponds where they occur in both clear and dark water, with the latter darkened by

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and Precipitation (chemistry), precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' is widel ...

s. They prefer to be in the vicinity of the cover of rocks, macrophytes or submerged wood. During the day they hide beneath stones or among vegetation. The adults remain hidden in the daylight hours and emerge to feed at night while the juveniles are more diurnal. Males attain sexual maturity after a year and females after two years, when the water levels rise in the winter rains in August and September they migrate upstream to headwaters and tributaries to breed. Each female can lay 230 to 1138 eggs. This is a carnivorous species which feeds on a variety benthic invertebrates, especially

ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

s and

fly larvae A maggot is the larva of a fly (order Diptera); it is applied in particular to the larvae of Brachycera flies, such as houseflies, cheese flies, hoverflies, and blowflies, rather than larvae of the Nematocera, such as mosquitoes and crane ...

. They have a lifespan of 6 years.

Conservation

The nightfish is only found in southwestern Australia. Although it occurs widely there, the area it occupies is only . It is threatened by invasive species, especially the

Eastern mosquitofish The eastern mosquitofish (''Gambusia holbrooki'') is a species of freshwater fish, closely related to the western mosquitofish, ''Gambusia affinis''. It is a member of the family Poeciliidae of order Cyprinodontiformes. The eastern mosquitofish i ...

(''Gambusia holbrooki''), which nip at their fins, and

rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributary, tributaries of the Pacific Ocean in North America and Asia. The steelhead (sometimes called steelhead trout) is an Fish migration#Classification, ...

(''Oncorhynchus mykiss'') and

European perch The European perch (''Perca fluviatilis''), also known as the common perch, redfin perch, big-scaled redfin, English perch, Euro perch, Eurasian perch, Eurasian river perch, Hatch, poor man's rockfish or in Anglophone parts of Europe, simply the ...

(''Perca fluviatilis'') which predate on it. It is also threatened by climate change which has caused the drying of habitats, secondary salinisation of rivers and the reductuion in the amount of available water on the

Swan Coastal Plain The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geol ...

The

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has assessed this species as

Near Threatened A near-threatened species is a species which has been Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...

References

{{Taxonbar, from=Q5505088 Percichthyidae Freshwater fish of Western Australia Fish described in 1873 Endemic fauna of Southwest Australia