Perccottus glenii
(Amur sleeper)

Preferred Common Name

• Amur sleeper

Other Scientific Names

• Eleotris dybowskii Herzenstein & Warpachowski, 1887
• Eleotris dybowskii Warpachowski, 1887
• Percottus glehni Dybowski, 1877

International Common Names

• English: Chinese sleeper; rotan

Local Common Names

• Finland: rohmutokko
• Germany: Chinesische; Schlafergrundel
• Hungary: Amur géb; Amurgéb
• Netherlands: Amurgrondel
• Poland: trawianka
• Russian Federation: goloveshka; rotan, goloveshka
• Serbia: Amurskog spavaca
• Slovakia: byckovec hlavaty

• Domain: Eukaryota
•     Kingdom: Metazoa
•         Phylum: Chordata
•             Subphylum: Vertebrata
•                 Class: Actinopterygii
•                     Order: Perciformes
•                         Suborder: Gobioidei
•                             Family: Odontobutidae
•                                 Genus: Perccottus
•                                     Species: Perccottus glenii

The specific epithet glenii is derived from the surname of the original collector, Glen, it may be misspelled as glehni or glenhi. Previously it has been placed in family Eleotridae (Berg, 1949; Nikolski, 1956).

Amur sleeper is a small/medium fish up to 20-25 cm total length. The shape of the body is typically streamlined like a perch. The body is robust, the depth at pelvic origin being about 30% of standard length. The mouth is large, the angle of the jaws is below the rear half of eye, the lower jaw is in advance of the upper jaw; the upper lip more or less uniform in width; the teeth are caniform. As with all fish from the Perciformes it has two dorsal fins. The pectoral fin tip is below the origin of the second dorsal fin. The pelvic fins are relatively short, less than 1/2 to 3/4 the length of the abdomen and about 3/5 to 3/4 of pectoral fin length. The caudal fin is rounded (Miller and Vasil’eva, 2003). The whole body is scaled. The meristic features for Amur sleeper are: D₁ VI-VIII, D₂ I-II/9-11, A I-III/7-10, P 14-16, V I/5 scales in lateral line l.l. 37-43 (Kirpichnikov, 1945; Berg, 1949; Miller and Vasil’eva, 2003).

Its coloration is rather dark and varies from greenish-olive to brownish-grey or dark green depending on water body character and colour of substrate. On the dorsal and lateral sides of the body it has dark, irregular spots and blotches with numerous small pale yellow to blue-green flecks; the belly speckled. A dark streak runs from the tip of snout to edge of opercula and from eye to angle of jaws.

The first dorsal fin has 3-4 dark pigmented streaks and similar pattern can be found on the caudal and anal fins. The dimorphism between the sexes (apart from during the breeding season) is not easily visible. The dorsal fins of males are slightly larger and closer to each other than in females. The ventral fins also differentiate the sexes as they are shorter and of different shape in males. Breeding males are much darker than females, sometimes almost black with distinct irregularly scattered bright bluish-green spots. Spots of the same colour, but arranged in even, horizontal rows are present on the dorsal and anal fins. Also in the breeding season males have inflated areas on the head.

The species first documented introduction outside its natural range distribution comes from 1912 when it was brought by the Russian naturalist I.L. Zalivskii near St. Petersburg (Lisiy Nos settlement) and four years later some individuals were released to a garden pond, from which they spread to other waterbodies (see Reshetnikov, 2001). In 1948, another introduction took place, the species was brought to Moscow by the participants of the Amur expedition (Spanovskaya et al., 1964; Bogutskaya and Naseka, 2002; Reshetnikov, 2004). Soon it appeared in the aquaria of amateurs and next in several ponds in Moscow and the Moscow Province. The other introductions were more unintentional as the Amur sleeper was translocated as contamination of stocking material of Asian herbivorous cyprinids e.g. Cyprinus carpio to fish farms from where it penetrated to open waters. One of the earliest examples of such introduction was the expansion of Amur sleeper from the Khabarovsk fish farm (Far East of Russia) to Gusinoe Lake (the Lake Baikal basin) in 1969. Similarly, it penetrated from the Ilevsk fish farm to waterbodies of the Nizhniy Novgorod Province in 1970-1971. Reshetnikov and Ficetola (2011) distinguished 13 centres of the Amur sleeper distribution outside of its native range - their location determined the shape of the current invaded range. According to these authors the invasion centre of Amur sleeper for Central Europe, i.e. Ukraine, Poland, Slovakia, Hungary, Serbia, Romania and Bulgaria, might be the fish farm near Lviv (Ukraine), where Amur sleeper had been introduced before 1980. However the series of independent accidental introductions of Amur sleeper (as contamination of stocking material) from different locations, including areas of the species native range distributions, is also possible considering the intensity of trade of stocking material of Asian cyprinids and number of purposeful introductions of these commercially important species both to ponds and open waters.

Natural Dispersal (Non-Biotic)

The Amur sleeper has naturally dispersed from several locations since its initial introduction. Reshetnikov and Ficetola (2011) distinguished 13 such dispersal centres for the present non-native distribution range. It is a rather bad swimmer and avoids main river courses; however, large rivers serve as long distance transport corridors downstream during high water levels and especially floods, when they are washed from adjacent oxbow lakes and flood plains, which they often inhabit (Košco et al., 2003a; Reshetnikov, 2010; Reshetnikov and Ficetola, 2011).

Accidental Introduction

The Amur sleeper has been accidentally introduced several times to many localities with stocking material of herbivorous cyprinids mainly Cyprinus carpio. It seems to be the most probable reason of its appearance in the Vistula and Danube river systems.

Intentional Introduction

The first specimens were translocated from their natural distribution area, i.e. the far east of Asia to Europe intentionally by a Russian naturalist and later by participants of Amur expeditions. The species is also known to be kept in aquaria (in Moscow in the 1950s it was available on a bird market) and was used as a live bait (Spanovskaya et al., 1964; Reshetnikov, 2004; 2010). Both were probably a source of uncontrolled local introductions by aquarists and anglers.

Litvinov and O’Gorman (1996) suggest the potential negative influence of Amur sleeper presence in the Selenga River (the Lake Baikal basin) on commercially important fish species such as Siberian roach (Rutilus rutilus lacustris) and Siberian dace (Leuciscus leuciscus baicalensis), as these species must now share food resources with Amur sleeper. Siberian roach and Siberian dace together accounted for about 50% of weight of commercial harvest in the Barguzin commercial area (Litvinov and O’Gorman, 1996).

Impact on Biodiversity

Amur sleeper is a predator with morphological features that enable hunting of a large variety of aquatic organisms with inclusion of relatively big prey items (Miller and Vasil’eva, 2003). When evaluating the potential impact of this species on ecosystems it might be concluded that several taxonomic groups of native hydrofauna, both macroinvetebrates and vertebrates would be potentially affected by the presence of this new predator. Its diet has been studied mostly in its native range (Sinelnikov, 1976) as well as in some invaded ecosystems in Russia (Spanovskaya et al., 1964; Litvinov and O’Gorman, 1996; Reshetnikov, 2001; 2003; 2008), Slovakia (Košco et al., 2008) and Poland (Grabowska et al., 2009). In all cases the species is reported to be a voracious predator with broad diet, constituting of crustaceans (Cladocera, Copepoda, Malacostraca), larvae and imagos of insects (Ephemeroptera, Odonata,  Hemiptera, Diptera, Trichoptera, Coleoptera), molluscs, fish and even larvae of amphibians (frogs and newts). Effects of the species predation on local aquatic communities in Russia were reported as deteriorative (Spanovskaya et al., 1964; Reshetnikov, 2001; 2003; 2008). Reshetnikov (2001; 2003) revealed that in small waterbodies Amur sleeper depressed populations of macroinvertebrates, as well as other fishes (e.g. Carassius carassius, Leucaspius delineatus), newts (Triturus cristatus, T. vulgaris) and frogs (Rana temporaria, R. arvalis, R. lessonae) that cannot reproduce successfully due to predation pressure, as the result the negative correlation between the presence and abundance of Amur sleeper and species richness of aquatic animals was observed. Long-term studies near Moscow (Spanovskaya et al., 1964) showed that the composition of consumed food changed along with alterations caused by Amur sleeper in local communities of available prey species. After abrupt impoverishment of large invertebrate fauna, and elimination of eggs, larvae and juveniles of crucian carp, tadpoles appeared in the predator’s diet and cannibalistic behaviour was noted. This shows Amur sleeper is an effective “switch-predator”.

Among hunted fish in the Wloclawski Reservoir (Poland) the most prevalent prey were cyprinids: bitterling Rhodeus sericeus, bleak Alburnus alburnus and roach Rutilus rutilus (Grabowska et al., 2009). According to Zaloznykh (1984), Amur sleeper preferred enamoured fish preys as compared to those that possess spines. However, in guts of large individuals from the Wloclawski Reservoir some sticklebacks, and even remains of spiny-cheek crayfish Faxonius limosus were also found in spring, probably because juveniles of unarmoured fish species were not available yet (Grabowska et al., 2009).

For some fish species native to central Europe like Umbra kramerii, Leucaspius delineatus, Carassius carassius, Rhodeus sericeus and larvae of other species, the Amur sleeper is a real threat not only due to predation but also as regards trophic competition (Košco et al., 2003b). It essentially causes them to disappear from the localities invaded by Amur sleeper. Under special concern should be native species of high conservation status like the mud minnow Umbra krameri in Slovakia and the swamp minnow Eupallasella percnurus in Poland (Wolnicki and Kolejko, 2008) as they show similar microhabitat requirements with Amur sleeper. These endangered and regionally highly endangered species locally suffer from Amur sleeper presence mainly due to predation. Similarly, in the Selenga River (the Lake Baikal basin) the invasion of Amur sleeper is expected to cause population decline of endemic fish species (Siberian roach, Rutilus rutilus lacustris and Siberian dace, Leuciscus leuciscus baicalensis) through resource competition and predation on their juveniles (Litvinov and O’Gorman, 1996).

It is expected that the recent rapid expansion of Amur sleeper in Central European waters will cause a serious threat to local aquatic communities.

• Proved invasive outside its native range
• Has a broad native range
• Highly adaptable to different environments
• Is a habitat generalist
• Capable of securing and ingesting a wide range of food
• Highly mobile locally
• Fast growing
• Has high reproductive potential

• Altered trophic level
• Modification of natural benthic communities
• Modification of nutrient regime
• Negatively impacts aquaculture/fisheries
• Reduced native biodiversity
• Threat to/ loss of endangered species
• Threat to/ loss of native species

• Competition - monopolizing resources
• Interaction with other invasive species
• Predation

• Highly likely to be transported internationally accidentally
• Highly likely to be transported internationally illegally
• Difficult/costly to control

The Amur sleeper does not have any human uses, economic value and social benefits, apart from use as bait (see Reshetnikov, 2001).