The Chinese sleeper (''Perccottus glenii''), also known as the Amur sleeper, 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 ...

freshwater sleeper Freshwater sleepers are a small family, the Odontobutidae, of gobiiform fishes native to freshwater rivers flowing into the South China Sea and the northwestern Pacific Ocean. The family consists of about 22 species in six genera. Genera The f ...

native to

Amur River The Amur (russian: река́ Аму́р, ), or Heilong Jiang (, "Black Dragon River", ), is the world's List of longest rivers, tenth longest river, forming the border between the Russian Far East and Northeast China, Northeastern China (Inne ...

basin in eastern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

with introduced populations in other regions of

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago a ...

. It is currently the only known member of its

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 ...

Description

The Chinese sleeper, known as rotan in Russia, resembles a

perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...

ruffe The Eurasian ruffe (''Gymnocephalus cernua''), also known as ruffe or pope, is a freshwater fish found in temperate regions of Europe and northern Asia. It has been introduced into the Great Lakes of North America, reportedly with unfortuna ...

sculpin A sculpin is a type of fish that belongs to the superfamily Cottoidea in the order Scorpaeniformes.Kane, E. A. and T. E. Higham. (2012)Life in the flow lane: differences in pectoral fin morphology suggest transitions in station-holding demand a ...

. The eyes are placed high on the head which has a rounded snout and projecting lower jaw. There is little or no gap between the two dorsal fins, the front one of which has six to eight spines and the back one nine to eleven soft rays. The anal fin has one to three spines and seven to ten soft rays. The pelvic fins are not fused together which helps to distinguish this fish from the

gobies Gobiidae or gobies is a family of bony fish in the order Gobiiformes, one of the largest fish families comprising more than 2,000 species in more than 200 genera. Most of gobiid fish are relatively small, typically less than in length, and the ...

. The second dorsal and the anal fins are both more rounded and shorter than the gobies and the caudal fin is also more rounded. The general colour is brownish with a checker-board pattern of darker marks or dark barring. There are dark lines on the head radiating from the eye. This species can reach a length of TL and the greatest recorded weight for a specimen is .

Distribution and habitat

The Chinese sleeper is native to the Far East but appeared in ponds in Eastern Europe in the early twentieth century and has since spread to large parts of the

Danube The Danube ( ; ) is a river that was once a long-standing frontier of the Roman Empire and today connects 10 European countries, running through their territories or being a border. Originating in Germany, the Danube flows southeast for , pa ...

, the

Vistula The Vistula (; pl, Wisła, ) is the longest river in Poland and the ninth-longest river in Europe, at in length. The drainage basin, reaching into three other nations, covers , of which is in Poland. The Vistula rises at Barania Góra in ...

and other river basins where it is considered an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

. Its typical habitat is ponds, closed water-bodies and slow-moving streams. The westernmost locality of the Chinese sleeper range is the ponds in the

Bavaria Bavaria ( ; ), officially the Free State of Bavaria (german: Freistaat Bayern, link=no ), is a state in the south-east of Germany. With an area of , Bavaria is the largest German state by land area, comprising roughly a fifth of the total lan ...

n Danube basin in

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

. A finding in the mesohaline environment is registered in the North-Western

Black Sea The Black Sea is a marginal mediterranean sea of the Atlantic Ocean lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia, Roma ...

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

Invasiveness

In Europe, the Chinese sleeper is included since 2016 in the list of Invasive Alien Species of Union concern (the Union list). This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union. At least one case of monospecific fish community composed of Chinese sleeper is registered in

Latvia Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...

. In the late summer of 2022, a small community of Chinese sleepers were found in a single pond in southwest Finland, the first record of the species in the country. This fish has been reported from Czechia recently https://www.biorxiv.org/content/10.1101/2023.01.20.524995v1

Behaviour

The Chinese sleeper is an adaptable species and tolerant of widely different conditions. It feeds on insects and their larvae, small crustaceans and fish fry. It spawns in warm shallows among vegetation and the male guards the eggs.

Economic importance

This species is of minor importance to local

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often ...

and has potential as an

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

fish. However, introduced populations are of concern as they could become detrimental to the local fauna due to its predatory nature and voracious appetite.

References

{{Taxonbar, from=Q10623625 Odontobutidae Fish of East Asia Fish of Russia Freshwater fish of China Fish of Korea Monotypic fish genera Taxa named by Benedykt Dybowski Fish described in 1877 Invasive animal species in Europe Invasive species in Ukraine