''Oxyeleotris nullipora'', the poreless gudgeon, is a

gudgeon A gudgeon is a socket-like, cylindrical (i.e., ''female'') fitting attached to one component to enable a pivoting or hinging connection to a second component. The second component carries a pintle fitting, the male counterpart to the gudgeon, ...

of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

Oxyeleotris ''Oxyeleotris'' is a genus of sleeper gobies mostly restricted to Australia and New Guinea, though some (''O. marmorata'', ''O. siamensis'', ''O. urophthalmoides'' and ''O. urophthalmus'') are found in Southeast Asia. They are found in a wide ra ...

'', a freshwater fish found in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

Description

The poreless gudgeon has a cylindrical body, a flattened head with a straight profile and a length of SL. The fish has two dorsal fins, the first being considerably smaller and the second about 67% as tall as the body is deep. Caudal and pectoral fins are rounded and the pelvic fins are slightly shorter than the pectorals. Colour is brown, darker on the dorsal surface fading to whitish on the belly and under the head. There is often a number of dark brown chevron like markings on the sides with a pair of dark blotches positioned at the upper and lower base of the tail fin. There are three dusky bands spreading backwards from the eye as well as a dark spot with a white centre above the pectoral fin base. The fins are generally clear to whitish and there are small dark spots on the dorsal fins giving the appearance of stripes with similar spots on the caudal fin forming vertical bands.

Distribution

The poreless gudgeon occurs in Cape York and

Arnhem Land Arnhem Land is a historical region of the Northern Territory of Australia, with the term still in use. It is located in the north-eastern corner of the territory and is around from the territory capital, Darwin. In 1623, Dutch East India Compan ...

in northern Australia and also southern New Guinea. Within

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

the fish ranges from around Ingham to

Cairns Cairns (, ) is a city in Queensland, Australia, on the tropical north east coast of Far North Queensland. The population in June 2019 was 153,952, having grown on average 1.02% annually over the preceding five years. The city is the 5th-most-p ...

, particularly the lower

Tully River The Tully River is a river located in Far North Queensland, Far North Queensland, Australia. Course and features The Tully River rises in the Cardwell Range, part of the Great Dividing Range on the northern boundary of the Kirrama State Fores ...

. There is a separate population in the

Hope Vale Hope Vale (also known as Hopevale) is a town within the Aboriginal Shire of Hope Vale and a coastal locality split between the Aboriginal Shire of Hope Vale and the Shire of Cook, both in Queensland, Australia. It is an Aboriginal community. I ...

region and the Cape York population ranges from the

Endeavour River The Endeavour River ( Guugu Yimithirr: ''Wabalumbaal''), inclusive of the Endeavour River Right Branch, the Endeavour River South Branch, and the Endeavour River North Branch, is a river system located on Cape York Peninsula in Far North Queen ...

up the eastern coast, around the tip and south to the

Edward River Edward River, or Kyalite River, an anabranch of the Murray River and part of the Murray–Darling basin, is located in the western Riverina region of south western New South Wales, Australia. The river rises at Picnic Point east of Mathoura, a ...

on the

Gulf of Carpentaria The Gulf of Carpentaria (, ) is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the eastern Arafura Sea (the body of water that lies between Australia and New Guinea). The northern boundary is ...

. The Arnhem Land population extends from the Reynolds River east to the Giddy River as well the

Tiwi Islands The Tiwi Islands ( tiw, Ratuati Irara meaning "two islands") are part of the Northern Territory, Australia, to the north of Darwin adjoining the Timor Sea. They comprise Melville Island, Bathurst Island, and nine smaller uninhabited islands, wi ...

. In New Guinea, the fish is found

Fly River The Fly River is the third longest river in the island of New Guinea, after the Sepik River and Mamberamo River, with a total length of and the largest by volume of discharge in Oceania, the largest in the world without a single dam in its catc ...

further west to around

Timika Timika is a chartered city (''kota''), and the capital of Mimika Regency on the southern coast of Central Papua, Indonesia. At the 2020 Census, the district which includes the town (it remains administratively within the Regency, rather than having ...

Habitat

''O.nulliporos'' is often found in wetlands on floodplains, smaller slow flowing creeks, backwaters and lily ponds where they tend to be found in the shallow margins among thick aquatic vegetation.. The fish is bottom dwelling and is found over a soft bottom in both clear and turbid water with a low pH.

Lifecycle/Reproduction

Spawning commence at temperatures above about . The female lays approximately 30 eggs, in diameter, on the underside of overhanging rocks and crevises. The eggs are translucent when laid and ovoid becoming darker as they develop. The male guards the eggs until they hatch in about 8 to 10 days. The newly hatched fry are about in length.

Utility to humans

Reportedly this species makes excellent aquarium fish but are rarely available in the hobby. They are one of Australia's smallest gudgeons and make peaceful aquarium subjects.

References

{{Taxonbar, from=Q5522690 Oxyeleotris Taxa named by Tyson R. Roberts Fish described in 1978