Silurus glanis ZBK Linnaeus, 1758
Inland water: 30900-876 (1 spc.), 05.07.1998 , Iznik Lake , M. Ôzulug , N. Meriç , Örner Altun .
- Nurettin Meriç, Lütfiye Eryilmaz, Müfit Özulug (2007): A catalogue of the fishes held in the Istanbul University, Science Faculty, Hydrobiology Museum. Zootaxa 1472, 29-54: 37-37, URL:http://www.zoobank.org/urn:lsid:zoobank.org:pub:428F3980-C1B8-45FF-812E-0F4847AF6786
Silurus glanis, sheatfish or wels catfish, is native to eastern Europe and Asia. It has been introduced to several other areas including Germany, France, Spain, England, Greece, Turkey and the Netherlands.
Biogeographic Regions: palearctic (Introduced , Native )
- Black, A. Predator-fishing.co.uk 2005. "Siluridae" (On-line). Accessed October 31, 2005 at http://www.predator-fishing.co.uk/articles/essay.htm.
The elongated, scaleless body has a strong upper body and a laterally flattened tail. Silurus glanis varies in color. The upper side is usually a dark color and the flanks and belly are more pale. The fins are brownish. The body has a mottled appearance that is sometimes accompanied by brown spots. These catfish can grow to be quite large, perhaps as large as 3 meters long. A maximum reported weight was 220 kg. Most individuals reach sizes between 1.3 and 1.6 meters. Silurus glanis reach an average of 45 kg and has been considered one of the largest freshwater fish in its range.
Silurus glanis individuals have 1 dorsal spine and 4 to 5 dorsal soft rays, 1 anal spine and 90 to 94 anal soft rays, and a caudal fin with 17 rays. They have paired pectoral fins with 1 spine and 14 to 17 soft rays each. Their paired pelvic fins are positioned behind the dorsal fin with 1 spine each and 11 to 12 soft rays each.
There are several members in the family Siluridae. Silurus glanis is distinguished by its smaller dorsal fin, only two pairs of barbels, and the caudal fin being distinct from the anal fin.
Sex can be determined by the flap of skin behind the vent, in males it is thin and comes to a point, females have a thicker and shorter flap of skin.
Range mass: 220 (high) kg.
Average mass: 45 kg.
Range length: 3 (high) m.
Average length: 1.3-1.6 m.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: sexes alike
Silurus glanis is found primarily in large rivers and lakes and in deep water near dams. These catfish sometimes enter brackish water in the Black Sea and Baltic Sea.
Range depth: 0 to 30 m.
Habitat Regions: temperate ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams; brackish water
- Froese, R., D. Pauly. 2005. "Silurus glanis" (On-line). Accessed October 31, 2005 at http://fishbase.org/Summary/speciesSummary.php?ID=289&genusname=Silurus&speciesname=glanis.
Habitat and Ecology
Large and medium size lowland rivers, backwaters and well vegetated lakes. Spawns in shallow, warm and well vegetated riverine habitats without current.
Lives up to 80 years in the wild. Spawns for the first time at 2-3 years and 1-2 kg. Spawns in April-June, in northern areas until August, when temperature reaches about 20°C. In spawning grounds, males defend small territories and build nests of plant material, dig shallow depressions or clean spawning substrate such as willow (Salix) roots. Nests are defended by males until larvae emerge. Spawns in pairs. During spawning act, the male embraces the female. Eggs hatch in 2-3 days and larvae remain in nest until yolk sack is absorbed (2-4 days). A nocturnal predator, feeding near bottom and in water column. Very sensitive to extra-aquatic sounds. Head sensory canal system allows to track the wakes [a trail of hydrodynamic and chemical signatures left by a swimming fish] of prey up to 10 seconds old over distances up to 55 times the length of the prey. Larvae and juveniles benthic and negatively phototactic, feeding on a wide variety of invertebrates and fish. Adults feed on fish and other aquatic vertebrates.
Silurus glanis fry feed on plankton during their first year of life. When they reach larger sizes they begin to eat worms, snails, crustaceans, aquatic insects, and small fish. At adult sizes they will also prey on ducks, voles, crayfish, fish, eels, frogs, rats, coypu, and snakes. They use the incredible suction created by suddenly opening their large mouths to take in prey.
Both the top and bottom jaws each have hundreds of inward sloping, soft teeth used to grip prey. There are two "crushing plates" in front of the throat cavity used to crush prey before swallowing. Silurus glanis manipulate their prey prior to consumption by using several short spikes along the edge of the gill rakers.
Animal Foods: birds; mammals; amphibians; reptiles; fish; carrion ; insects; mollusks; terrestrial worms; aquatic crustaceans; zooplankton
Plant Foods: phytoplankton
Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore ); planktivore
Silurus glanis carry bacterial diseases that can be transmitted to other fish. They are important predators of fish, crustaceans, small mammals, and aquatic birds.
- "red head disease" (Vibrio sp. bacterium)
- "gill disease" (Flavobacterium)
- Farkas, J. 1985. Filamentous Flavobacterium sp. isolated from fish with gill diseases in cold water. Aquaculture, Volume 44, Issue 1: 1-10. Accessed November 01, 2005 at http://www.sciencedirect.com/science?_ob=ArticleURL&_aset=V-WA-A-W-WC-MsSAYZA-UUA-U-AABBVCECUZ-AABAUVUBUZ-VVVVYWDYC-WC-U&_rdoc=21&_fmt=summary&_udi=B6T4D-49NPK1V-XH&_coverDate=01%2F15%2F1985&_cdi=4972&_orig=search&_st=13&_sort=d&view=c&_acct=C000043360&_version=1&_urlVersion=0&_userid=4159506&md5=d2cb75770e5fd2588d18061914f5a4c3.
- Farkas, J., M. Szitóné. 1986. Vibrio disease of sheatfish (Silurus glanis L.) fry. Aquaculture, Volume 51, Issue 2: 81-88. Accessed November 01, 2005 at http://www.sciencedirect.com/science?_ob=ArticleURL&_aset=V-WA-A-W-WC-MsSAYZA-UUA-U-AABBVCECUZ-AABAUVUBUZ-VVVVYWDYC-WC-U&_rdoc=20&_fmt=summary&_udi=B6T4D-49NXD4X-1SC&_coverDate=01%2F01%2F1986&_cdi=4972&_orig=search&_st=13&_sort=d&view=c&_acct=C000043360&_version=1&_urlVersion=0&_userid=4159506&md5=1be4cd970b7851ee99258854225eb8d9.
Northern pike (Esox lucius) and humans are two predators of Silurus glanis. Their large size protects adults from many predators. Smaller fish may be protected somewhat by their dorsal spines.
- northern pike (Esox lucius)
- humans (Homo sapiens)
Diseases and Parasites
Life History and Behavior
Silurus glanis individuals use their barbels and olfactory buds to sense chemical cues in the water. They are thought to be extraordinarily sensitive to chemical stimuli. They also have a lateral line system that helps them detect water movement. Silurus glanis individuals may use path analysis to track prey. One study found that S. glanis can track the three-dimensional swim path of a guppy and successfully attack it without the presence of light. Little is known about communication in these mainly solitary animals.
Perception Channels: tactile ; chemical
- Bridgeman, G. Predator-fishing.co.uk 2005. "The 'Old World' catfish, Silurus.glanis; it's evolutionary success story and unrivalled feeding strategy" (On-line). Accessed October 31, 2005 at http://www.predator-fishing.co.uk/articles/outwiththeold.htm.
The larvae hatch in approximately 3 days, measuring around 7 mm, and begin feeding on plankton. These fish grow quickly and can reach between 1.5 and 4.5 kg in their first year.
- ALP, A., C. KARA, H. BUYUKUAPAR. 2004. Reproductive Biology in a Native European Catfish, Silurus glanis. Turkey Journal of Veterinary Animal Science, 28: 613-622. Accessed December 07, 2005 at http://journals.tubitak.gov.tr/veterinary/issues/vet-04-28-3/vet-28-3-24-0303-29.pdf.
The longest know lifespan in the wild is 80 years old for S. glanis. The expected lifespan in the wild is as high as 20 to 30 years old.
Status: wild: 80 (high) years.
Status: wild: 20 to 30 years.
Status: wild: 20 to 30 years.
Status: captivity: 60 years.
Lifespan, longevity, and ageing
There is little known about mating behavior in this species. Males create nests where females deposit their eggs. Males then guard the eggs until they hatch.
Mating System: polygynandrous (promiscuous)
The male creates a shallow depression that will hold thousands of eggs laid by the female. The eggs are protected by the male until they hatch. Females can lay about 30,000 eggs per kilogram of body weight. Males grow faster and mature earlier than females. One study found that males matured at 78.82 cm at age 3 and females matured at 87.05 cm at age 4.
Breeding interval: Wels catfish breed annually during the spring.
Breeding season: Breeding/spawning season runs from May through July.
Range gestation period: 3 to 10 days.
Range time to independence: 3 to 10 days.
Average age at sexual or reproductive maturity (female): 4 years.
Average age at sexual or reproductive maturity (male): 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
Average age at sexual or reproductive maturity (male)
Sex: male: 912 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 1277 days.
The male protects the eggs until they hatch.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Male)
- Black, A. Predator-fishing.co.uk 2005. "Siluridae" (On-line). Accessed October 31, 2005 at http://www.predator-fishing.co.uk/articles/essay.htm.
Molecular Biology and Genetics
Barcode data: Silurus glanis
Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.
See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
Statistics of barcoding coverage: Silurus glanis
Public Records: 38
Specimens with Barcodes: 45
Species With Barcodes: 1
Silurus glanis populations appear to be stable. They are protected by Appendix III of the Bern Convention. In areas where these fish have been introduced, negative ecological consequences have been noted.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
Relevance to Humans and Ecosystems
Silurus glanis introductions have been implicated in declining populations of other commercial fishes.
Silurus glanis is a commercial fish consumed by humans. This fish has boneless white flesh that is low in fat and highly palatable. Technological research for artificial reproduction, population genetics and conservation problems have been developed over the past 10 years in the Czech Republic, France and other European countries. It is also a valued game fish in European countries.
Positive Impacts: food
- Linhart, O., L. Stech, J. Svarc, M. Rodina, J. Audebert, J. Grecu, R. Billard. 2002. The culture of the European catfish, Silurus glanis, in the Czech. Aquatic Living Resources, 15: 139-144. Accessed December 08, 2005 at http://www.edpsciences.org/articles/alr/pdf/2002/02/alr2099.pdf?access=ok.
The wels catfish (// or //; Silurus glanis), also called sheatfish, is a large catfish native to wide areas of central, southern, and eastern Europe, and near the Baltic and Caspian Seas. It has been introduced to Western Europe and is now found from the United Kingdom all the way east to Kazakhstan and south to Greece. It is a scaleless fresh and brackish water fish recognizable by its broad, flat head and wide mouth. Wels catfish can live for at least thirty years and have very good hearing.
The wels catfish lives on annelid worms, gastropods, insects, crustaceans, and fish including other catfishes; the larger ones also eat frogs, mice, rats, and aquatic birds such as ducks. Recently, individuals of this species in environments that are not their native habitats have been observed lunging out of the water to grab pigeons on land.
The wels catfish lives in large, warm lakes and deep, slow-flowing rivers. It prefers to remain in sheltered locations such as holes in the riverbed, sunken trees, etc. It consumes its food in the open water or in the deep, where it can be recognized by its large mouth. Wels catfish are kept in fish ponds as food fish.
Wels catfish's mouth contains lines of numerous small teeth, two long barbels on the upper jaw and four shorter barbels on the lower jaw. It has a long anal fin that extends to the caudal fin, and a small sharp dorsal fin positioned relatively far forward. It uses its sharp pectoral fins to capture prey. With these fins, it creates an eddy to disorient its victim, which it then simply engulfs in its enormous throat. It has very slippery green-brown skin. Its belly is pale yellow or white. Colour varies with environment. Clear water will give the fish a black coloration while muddy water will often tend to produce brownish specimens. Weight and length are not correlated linearly, and also depend on the season.
The female produces up to 30,000 eggs per kilogram of body weight. The male guards the nest until the brood hatches, which, depending on water temperature, can take from three to ten days. If the water level decreases too much or too fast the male has been observed to splash the eggs with its muscular tail in order to keep them wet.
With a possible total length up to 4 m (13 ft) and a maximum weight of over 400 kg (880 lb) it is the second largest freshwater fish in its region after the beluga sturgeon. However, such lengths are extremely rare and could not be proved during the last century, but there is a somewhat credible report from the 19th century of a wels catfish of this size. Brehms Tierleben cites Heckl's and Kner's old reports from Danube about specimens 3 m (9.8 ft) long and 200–250 kg (440–550 lb) in weight, and Vogt's 1894 report of a specimen caught in Lake Biel which was 2.2 m (7 ft 3 in) long and weighed 68 kg (150 lb). In 1856, K. T. Kessler wrote about specimens from Dniepr which were over 5 m (16 ft) long and weighed up to 400 kg (880 lb).
Most wels catfish are only about 1.3–1.6 m (4 ft 3 in–5 ft 3 in) long; fish longer than 2 m (6 ft 7 in) are normally extremely rare. At 1.5 m (4 ft 11 in) they can weigh 15–20 kg (33–44 lb) and at 2.2 m (7 ft 3 in) they can weigh 65 kg (143 lb).
Only under exceptionally good living circumstances can the wels catfish reach lengths of more than 2 m (6 ft 7 in), as with the record wels catfish of Kiebingen (near Rottenburg, Germany), which was 2.49 m (8 ft 2 in) long and weighed 89 kg (196 lb). This giant was surpassed by some even larger specimens from Poland (2,61 m. 109 kg.), Ukraine, France, Spain (in the River Ebro), Italy (in the Po River and Arno River), and Greece, where this fish was released a few decades ago. Greek wels grow well thanks to the mild climate, lack of competition, and good food supply. The largest accurate weight was 144 kg (317 lb) for a 2.78 m (9 ft 1 in) long specimen from the Po Delta in Italy. Other reports of larger wels (around 5 m (16 ft) or more) are unlikely and are often regarded as typical big fish stories or in some cases misidentification of the now rare sturgeon.
Exceptionally large specimens are rumored to attack humans in rare instances, a claim investigated by extreme angler Jeremy Wade in an episode of the Animal Planet television series River Monsters following his capture of three fish, two of about 66 kg (145 lb) and one of about 73 kg (160 lb), of which two attempted to attack him following their release. A report in the Austrian newspaper Der Standard on 5 August 2009, mentions a wels catfish dragging a fisherman near Győr, Hungary, under water by his right leg after the man attempted to grab the fish in a hold. The man barely escaped with his life from the fish, which must have weighed over 100 kg (220 lb), according to the fisherman.
There are concerns about the ecological impact of introducing the wels catfish to non-native regions. These concerns take into account the situation in Lake Victoria in Africa, where Nile perch (available in stores as Lake Victoria perch) were introduced and rapidly caused the extinction of numerous indigenous species. This severely impacted the entire lake, destroying much of the original ecosystem. The introduction of foreign species is almost always a burden on the affected ecosystem. Following the introduction of wels catfish, some fishes' numbers are in clear and rapid decline. Since its introduction in the Mequinenza Reservoir in 1974, it has spread to other parts of the Ebro basin, including Ebro and its tributaries, especially the Segre River. Some endemic species of Iberian barbels, genus Barbus in the Cyprinidae, were once abundant especially in the Ebro river but due to competition from and predation by wels catfish have since disappeared in the middle channel Ebro. The ecology of the river has also changed, as there is now a major growth in aquatic vegetation such as algae. Barbel species from mountain stream tributaries of the Ebro that wels catfish have not colonized are not affected.
As a food fish
Only the flesh of young Silurus glanis specimens is valued as food. It is palatable when the catfish weighs less than 15 kg (33 lb). Larger than this size, the fish is highly fatty and not recommended for consumption.
- Aristotle's catfish (Silurus aristotelis) from Greece, the only other native European catfish species beside Silurus glanis.
- Amur catfish (Silurus asotus), introduced to European rivers
- Giant lake biwa catfish (Silurus biwaensis) from Japan endemic to Lake Biwa.
- Silurus soldatovi from Russia
- Mekong giant catfish on the lower reaches of the Mekong
- Cucherousset, J.; Boulêtreau, S. P.; Azémar, F. D. R.; Compin, A.; Guillaume, M.; Santoul, F. D. R. (2012). Steinke, Dirk, ed. ""Freshwater Killer Whales": Beaching Behavior of an Alien Fish to Hunt Land Birds". PLoS ONE 7 (12): e50840. doi:10.1371/journal.pone.0050840.
- Brehm, Alfred; Brehms Tierleben II - Fish, Amphibians, Reptiles 1
- Mareš, Jaroslav; Legendární příšery a skutečná zvířata, Prague, 1993
- Wood, Gerald C. (1982). The Guinness book of animal facts and feats. Enfield, Middlesex: Guinness Superlatives. ISBN 0-85112-235-3.
- Der Standard, 2009-08-05. Waller-Wrestling im ungarischen Fischerteich. Retrieved 2009-08-06. (German)
- World Conservation Monitoring Centre (1996). Silurus glanis. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 9 May 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Silurus glanis" in FishBase. March 2006 version.
- "Silurus glanis". Integrated Taxonomic Information System. Retrieved 19 March 2006.