''Gobiomorphus coxii'', or Cox's gudgeon, is a species of sleeper goby in 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 ...

Eleotridae Eleotridae is a family of fish commonly known as sleeper gobies, with about 34 genera and 180 species. Most species are found in the tropical Indo-Pacific region, but there are also species in subtropical and temperate regions, warmer parts of t ...

which is native to the upland rivers of south eastern Australia.

Description

''Gobiomorphus coxii'' is dark brown to greenish-brown in colour on the back and flanks, this colouration fades to pale brown or cream on the underside. The scales on the lower flanks are mottled with blue, gold and yellow and there is a single black spot above the base of the

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

. The juveniles have series of elongated blotches on their flanks which merge as they nature to create a wide, dusky, mid-lateral stripe. The head is dark brown with the lower jaw and throat often coloured black and with two indistinct, dark stripes radiating from the rear of the orbit across operculum. Its fins vary from colourless to blackish-grey and 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 ...

s have between one and three dark stripes with a yellow or orange background colour. The margins of the fin are frequently fin margins yellow and the

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 ...

is marked with many dark spots which are arranged in irregular bands. The body of ''Gobiomorphus coxii'' is nearly cylindrical and tapers towards the tail, the head is large with a blunt, round snout and the quite small eyes are positioned high on the head. The mouth is relatively large, oblique and turned upwards with the lips ending lust below the front part of the eyes. They have jaws armed with bands of fine, pointed teeth. The cheek and operculum have lines of papillae which are also found around the preopercular margin and on each side of snout to above the eye. There are 3-5 large pores on the preopercular margin. It has two dorsal fins, the first, anterior dorsal fin, is rounded and has notches between its six spines and the second, posterior dorsal fin, is taller and slightly longer. 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 ...

is below the second dorsal fin but it is smaller and rounder. The caudal fin is quite large and is, truncated while the pectoral fins are also large and are rounded and the rather long, pointed

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s are located on the thorax. Males grow to a maximum

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 ...

of but are more commonly , but the females grow larger than the males.

Distribution and habitat

''Gobiomorphis coxii'' 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 ...

to eastern Australia from southern

Queensland Queensland ( , commonly abbreviated as Qld) is a States and territories of Australia, state in northeastern Australia, and is the second-largest and third-most populous state in Australia. It is bordered by the Northern Territory, South Austr ...

Gippsland Gippsland () is a rural region in the southeastern part of Victoria, Australia, mostly comprising the coastal plains south of the Victorian Alps (the southernmost section of the Great Dividing Range). It covers an elongated area of east of th ...

. It also occurs in the Swan River in

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 ...

where it is thought to be an

Introduced species An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...

. This species occurs in coastal and inland freshwaters up to around in altitude where it is normally found in upland streams with reasonable fats currents, even in rapids.

Biology

The populations of ''Gobiomorphus coxii'' appear to be more abundant in the more southerly rivers in its range, it is especially numerous in flowing areas, even rapids.. The adults do not occur in the lower reaches and they range upstream up to and they are rare near the sea. They have been recorded ascending dam walls and waterfalls using their pectorals even outside of the water flow. The adults feed on aquatic insects and on

mosquitofish The western mosquitofish (''Gambusia affinis'') is a North American freshwater poeciliid fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, ''Gambusia'', or by the common name gambezi. Its sister species ...

. The juveniles are generally found in the lower reaches of rivers, closer to their mouths and migrate up stream as they mature. Females lay eggs onto rocky surfaces which are the guarded and fanned by the male for several days until they hatch into free-swimming larvae which are carried downstream.

References

{{taxobar, from=Q6418419 Taxa named by Gerard Krefft coxii