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

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of freshwater

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fishes, is a class of bony fish. They comprise over 50% of living vertebrate species. The ray-finned fishes are so called because their fins are webs of skin supported by bony or h ...

, a

temperate perch The members of the family Percichthyidae are known as the temperate perches. They belong to the order Perciformes, the perch-like fishes. The name Percichthyidae derives from the Latin ''perca'' for perch and Ancient Greek ἰχθύς, ''ichthy ...

from the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Percichthyidae The members of the family Percichthyidae are known as the temperate perches. They belong to the order Perciformes, the perch-like fishes. The name Percichthyidae derives from the Latin ''perca'' for perch and Ancient Greek ἰχθύς, ''ichthy ...

which is

endemic Endemism is the state of a species being found 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 found else ...

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

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 naturalist, known also as François Laporte or Francis de Castelnau. The stand ...

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

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. 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 "unispe ...

genus ''Bostockia'' for this new species. The is genus is classified within the family Percichthyidae, the temperate perches. The genus name honours the Anglican 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 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 located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

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

caudal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

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 is , although most fish are around .

Distribution

The nightfish is endemic to the coastal wetlands of Southwest Australia. 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 waters and in waters darkened by

tannin Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids. The term ''tannin'' (from Anglo-Norman ''tanner'' ...

s. They prefer to be in the vicinity of the cover of rocks, macrophytes or submerged wood. It hides during the day, 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 of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typi ...

s and fly larvae. They have a lifespan of 6 years.

Conservation

The nightfish is only found in southwestern Australia. Although it occ=urs 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 mosquitofis ...

(''Gambusia holbrooki''), which nips the fins of the nightfish, and rainbow trout (''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 th ...

(''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 IUCN has assessed this species as

Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify f ...

References

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