''Hypseleotris compressa'', the empire gudgeon, is a species of Gobiiform fish in the family

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 th ...

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 elsew ...

to Australia and south-central

New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...

Taxonomy

Gerard Krefft Johann Ludwig (Louis) Gerard Krefft (17 February 1830 – 19 February 1881), a talented artist and draughtsman, and the Curator of the Australian Museum for 13 years (1861-1874), was one of Australia's first and most influential zoologists and ...

described the empire gudgeon in 1864 as ''Eleotris compressus'', having been discovered by one James F. Wilcox.

Description

''H. compressa'' has an elongated body which can be up to long. The males are larger than the females. The fish does not have a

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 epithelial ...

, but does have

ctenoid A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as ...

scales. Its color varies, but the fish generally has a yellowish-tan to golden-brown head, although it can occasionally be a dark brown. Its abdomen is usually a whitish-red color. During the off-breeding seasons, males can be identified by prominent, variously colored bands on their anal and dorsal fins. The caudal fin is a "dusky" colour, and the pectoral and pelvic fins have no colour. During the breeding season, the male's colors brighten significantly, turning a red-orange colour, and they sometimes appear to glow. The male fish uses his colors to attract a mate. The species can quickly change color as needed.

Distribution and habitat

The ''H. compressa'' population is mostly concentrated in the northern and eastern portions of Australia and south-central

. It has also been found in the

Torres Strait The Torres Strait (), also known as Zenadh Kes, is a strait between Australia and the Melanesian island of New Guinea. It is wide at its narrowest extent. To the south is Cape York Peninsula, the northernmost extremity of the Australian mai ...

, around

Muralag The Prince of Wales Island, or Muralag, is an island of the Torres Strait Islands archipelago at the tip of Cape York Peninsula within the Endeavour Strait of Torres Strait in Queensland, Australia. The island is situated approximately north ...

and Horn Island. The fish is most commonly found in freshwater flowing rivers or streams, but is also found in still water and can withstand sea water level salinity. It is usually found in the lower reaches of rivers, but can also live upstream. It swims amongst aquatic plants and branches, and sometimes hides among rocks, using them as "caves".

Behaviour

The fish is

omnivorous An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutri ...

, primarily taking small crustaceans and insects but will also consume algae and aquatic plants. Spawning usually occurs in fresh water during warm weather; the breeding season generally spans from spring to autumn. After spawning with the male, the female fish lays rows of about 3,000 adhesive-coated eggs, each of which are about .32 mm long. The eggs stick to various surfaces, such as plants, logs, rocks, or sand. The male then fertilizes them with "sperm lines". The male guards the eggs until the young fish hatch, which usually takes 10–14 hours. After hatching, the young fish go downstream to

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

, where their development takes place. Once grown, the fish return to fresh water. This spawning strategy, coupled with the very small size of the newborn fry, has hindered efforts at propagating this species for aquariums, though it has been accomplished by accident in shrimp aquaculture ponds. A controlled study comparing six native fish species with the introduced (and invasive)

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 ...

(''Gambusia holbrooki'') on consuming larvae of the common banded mosquito (''

Culex annulirostris ''Culex annulirostris'', commonly known as the common banded mosquito, is an insect native to Australia, Fiji, Micronesia, the Philippines and Indonesia. It is regarded as a serious pest species throughout its range. Frederick Askew Skuse desc ...

'') in Brisbane found that the empire gudgeon was as efficient at eating mosquito larvae as the eastern mosquitofish and is a good candidate for mosquito control.

References

{{Taxonbar, from=Q5680000 compressa Freshwater fish of Australia Freshwater fish of New Guinea Fish described in 1864 Taxa named by Gerard Krefft