Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Anguillicoloides crassus



Anguillicoloides crassus


  • Last modified
  • 14 July 2018
  • Datasheet Type(s)
  • Invasive Species
  • Natural Enemy
  • Preferred Scientific Name
  • Anguillicoloides crassus
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Nematoda
  •       Class: Secernentea
  •         Subclass: Spiruria
  • Summary of Invasiveness
  • A. crassus is native to eastern Asia where it is a widespread, non-pathogenic parasite of the swimbladder of Anguilla japonica. Introduced to Germany with imported Japanese eels around 1980, it transferred...

Don't need the entire report?

Generate a print friendly version containing only the sections you need.

Generate report


Top of page
Anguillicola crassus; nematodes in body cavity, Lough Derg, Ireland.
TitleNematodes in body cavity
CaptionAnguillicola crassus; nematodes in body cavity, Lough Derg, Ireland.
CopyrightDan Minchin
Anguillicola crassus; nematodes in body cavity, Lough Derg, Ireland.
Nematodes in body cavityAnguillicola crassus; nematodes in body cavity, Lough Derg, Ireland.Dan Minchin
Anguillicola crassus; isolated nematodes from eels on Lough Derg, Ireland.
TitleIsolated nematodes
CaptionAnguillicola crassus; isolated nematodes from eels on Lough Derg, Ireland.
CopyrightDan Minchin
Anguillicola crassus; isolated nematodes from eels on Lough Derg, Ireland.
Isolated nematodesAnguillicola crassus; isolated nematodes from eels on Lough Derg, Ireland.Dan Minchin


Top of page

Preferred Scientific Name

  • Anguillicoloides crassus (Kuwahara, Niimi et Itagaki, 1974)

Other Scientific Names

  • Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974

International Common Names

  • English: anguillicolosis; swim bladder worm; swimming bladder worm

Local Common Names

  • Denmark: svømmeblæreorm
  • Germany: Schwimmblasenwurm
  • Netherlands: zwemblaasworm
  • Poland: angwilikola
  • Sweden: simblåsemask

Summary of Invasiveness

Top of page

A. crassus is native to eastern Asia where it is a widespread, non-pathogenic parasite of the swimbladder of Anguilla japonica. Introduced to Germany with imported Japanese eels around 1980, it transferred to the European eel Anguilla anguilla and has subsequently spread throughout Europe and northern Africa. Following introduction to America, in less than 20 years it has spread from Texas to Cape Breton in Anguilla rostrata. It has the attributes of an excellent coloniser, including high fecundity, low intermediate host specificity and the ability to use a wide range of freshwater fish as paratenic hosts. These, and the uncontrolled transfers of live eels by man, have facilitated its spread and made it the most invasive helminth known. It can be highly pathogenic to Atlantic eels, damaging swimbladders and able to cause mortalities. It affects eels’ swimming abilities and it is feared that it reduces their ability to migrate to their marine spawning grounds.

Taxonomic Tree

Top of page
  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Nematoda
  •             Class: Secernentea
  •                 Subclass: Spiruria
  •                     Order: Camallanida
  •                         Suborder: Camallanina
  •                             Family: Anguillicolidae
  •                                 Genus: Anguillicoloides
  •                                     Species: Anguillicoloides crassus

Notes on Taxonomy and Nomenclature

Top of page
The superfamily Anguillicoloidea contains only one family, Anguillicolidae Yamaguti, 1935. This is now considered (Moravec, 2006) to contain two genera, Anguillicola with a single species and Anguillicoloides with four species. Anguillicoloides crassus (Kuwahara, Niimi et Itagaki, 1974) Moravec and Taraschewski, 1988 is thus the correct nomenclature for the species that has hitherto, and in the great majority of the literature until recently, been referred to as Anguillicola crassus.

Adults of all five species are parasitic in the swim bladders of eels of the genus Anguilla. The preferred host of each is a species of Pacific eel and their heartland and the original area of their distribution is in Asia and Africa, i.e. in countries bordered by the Pacific and Indian oceans. Thus, Anguillicola globiceps Yamaguti, 1935 is a parasite of Anguillajaponica and its native distribution is in China and Japan. A. crassus is probably widespread throughout China, Japan and Korea and its preferred host there is also Anguilla japonica, but Moravec (2006) believes that it may have been introduced into Japan with imports of eels and that its region of origin is elsewhere in the Pacific. The antipodean species Anguillicoloides australiensis (Johnston and Mawson, 1940) Moravec and Taraschewski, 1988 is restricted to Australia and (probably) New Zealand, and infects the long-finned eels Anguilla reinhardtii and, probably, Anguilla dieffenbachii. The other antipodean species, Anguillicoloides novaezelandiae Moravec and Taraschewski, 1988, is a native of New Zealand but also occurs in Australia, and it infects the short-finned eel Anguilla australis. The remaining species, Anguillicoloides papernai Moravec and Taraschewski, 1988, is a native of South Africa and infects the African long-finned eel Anguilla mossambica. It would seem possible that there may be other species in the genus still to be described which infect other species of Pacific eels, but the parasite fauna of these species is still very poorly known. There are no species of anguillicolid native to the Atlantic eels Anguilla anguilla and Anguilla rostrata.
In the past there has been considerable confusion in identification of the species, due only in part to inadequate descriptions. This has now been rectified by the full descriptions of each species and the provision of keys (Moravec and Taraschewski, 1988; Moravec, 1994, 2006). Confusion has also arisen in part because two species, Anguillicoloides novaezelandiae and Anguillicoloides crassus,have been introduced into Europe with their natural eel hosts. In 1982, Anguillicoloides novaezelandiae was identified erroneously as Anguillicoloides australiensis in eels Anguilla anguilla in Bracciano lake in Italy (Paggi et al., 1982). The species is still present in the lake but appears to be being replaced there by Anguillicoloides crassus (Moravec et al., 1994a). Although it is now believed that all other records of Anguillicoloides from Europe refer to Anguillicoloides crassus, at the time of its first appearance on this continent there was some confusion with Anguillicola globiceps. However, Taraschewski et al. (1987) have confirmed that the specimens in Germany and Japan do belong to the same species. It is highly likely that Anguillicola globiceps has been introduced into Europe with Pacific eels but there is no record of its having established itself on this continent.


Top of page

It would appear that A. crassus was originally restricted to East Asia throughout which it is probably widespread and endemic, especially in China, Japan, Korea and Taiwan (there are not many records of its being definitely identified in China, probably because as a non-pathogenic species it is likely to be considered unimportant, and because of its similarity to Anguillicola globiceps). It is likely that it is present in other countries in this region and it has been reported from Thailand (Moravec, 2006) but there have been very few or no published reports of eel parasites from many parts of Eastern Asia. Its natural range probably coincides with that of its preferred host Anguilla japonica.

Factors limiting distribution
Although A. crassus is potentially able to infect Atlantic eels throughout their entire range and has a wide tolerance of environmental conditions, it also exhibits a preference for some physico-chemical conditions, notably of temperature and salinity.
Although present in the Baltic Sea, A. crassus was slow to colonise the Nordic countries of Norway and Sweden, and Finland is still believed to be free of infection. When it was first reported from Sweden, it was from coastal areas where water temperatures were raised by thermal effluents from power stations (Hoglund et al, 1992). Only much later was it reported from inland waters (Hoglund and Thomas, 1992).
The temperature tolerance of A. crassus was investigated experimentally by Knopf et al. (1998) who infected Anguilla anguilla and maintained them over a range of temperatures for 4 months. They found that larval development was significantly retarded at low temperatures. Larval L3 could survive 4 months at 4° C, but were unable to invade the swimbladder wall. Adults exhibited decreased growth and reproduction rates and increased mortality compared to those kept at 18° C. These data thus support the conclusions drawn from field studies that the spread of the parasite in boreal regions may be restricted by temperature.
Field data have indicated that although A. crassus is primarily a freshwater species, it can nevertheless tolerate enhanced salinity levels. Køie (1988, 1991) found that whilst the parasite could survive enhanced salinity in the Baltic sea, it was normally absent from sea water eel farms. Reimer et al. (1994) also noted that the distribution of A. crassus in the Baltic sea indicated that it was tolerant of, and able to be transmitted under, conditions of enhanced salinity. The parasite has also been reported to be able to survive in eels in the tidal reaches of the River Thames (Pilcher and Moore, 1993) and in Italian coastal lagoons with slightly enhanced salinity, although not in the most saline ones (Kennedy et al., 1997; Di Cave et al., 2001).
In experimental laboratory studies Kennedy and Fitch (1990) showed that the proportion of eggs hatching decreased with increasing salinity such that only 6% hatched in 100% seawater. The survival of L2s also declined with increasing salinity but even though 50% survived 10 days in 100% seawater, larval infectivity declined and none survived longer than 15 days. Similar findings were reported by De Charleroy et al. (1990).
Kennedy and Fitch (1990) also reported that there was no loss of viability of adults or L4s or eggs of A. crassus in Anguilla anguilla maintained in full sea water for up to 4 weeks. More detailed studies on survival of A. crassus in saline conditions were undertaken by Scholz and Zerbst-Boroffka (1994), who found that its body fluids were isosmotic with those of the eel host (Anguilla anguilla), but differed in ionic composition, and by Kirk et al. (2000a, b; 2002). These authors found that adult parasites tolerated seawater by osmoconformation with the blood plasma of their eel hosts. The majority of parasites (90%) osmoconformed with hosts after 2 weeks in sea water following acute transfer and survived for a long period, up to and exceeding 3 months. A small proportion of pre-adults and adult parasites were unable to withstand the osmotic stress and died, but the reasons for this are not known. These same authors concluded that whilst A. crassus was unable to be transmitted to eels in seawater, due to the absence of suitable copepod hosts, it could be transmitted in estuaries using species such as Eurytemora affinis and it could survive the transition to sea water in eels already infected in freshwater, and continue to survive and reproduce in them for up to 6 months. It was thus possible for the parasite to be disseminated naturally by eel movements in coastal waters.

Distribution Table

Top of page

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes


ChinaPresentPresent based on regional distribution.
-FujianPresentNativeNagasawa et al., 1994In culture
-HubeiPresentNativeNagasawa et al., 1994In culture
JapanPresentPresent based on regional distribution.
-HokkaidoWidespreadNativeNagasawa et al., 1994Especially in culture
-HonshuWidespreadNativeNagasawa et al., 1994Culture in wild
Korea, Republic ofPresentNativeKim et al., 1989Reported from culture
TaiwanWidespreadNativeMünderle et al., 2006Wild and in culture
ThailandPresentMoravec, 2006
TurkeyPresentIntroduced Invasive Genç et al., 2005In several rivers


EgyptPresentIntroduced Invasive Mohamed and Nouh, 2004
MoroccoLocalisedIntroduced Invasive Loukilli and Belghyti, 2007Known since 1999
RéunionLocalisedIntroduced Invasive Sasal et al., 2008Reported from African eel species, and believed to have been introduced by man
TunisiaLocalisedIntroduced Invasive Maamouri et al., 1999In one lake system, but extending range

North America

CanadaPresentPresent based on regional distribution.
-New BrunswickWidespreadIntroduced Invasive Aieta and Oliveira, 2009
-Newfoundland and LabradorWidespreadIntroduced Invasive Aieta and Oliveira, 2009
-Nova ScotiaWidespreadIntroduced Invasive Aieta and Oliveira, 2009
-Prince Edward IslandWidespreadIntroduced Invasive Aieta and Oliveira, 2009
USAPresentPresent based on regional distribution.
-MaineWidespreadIntroduced Invasive Aieta and Oliveira, 2009
-MarylandWidespreadIntroduced Invasive Barse et al., 2001
-MassachusettsWidespreadIntroduced Invasive Aieta and Oliveira, 2009
-New YorkLocalisedIntroduced Invasive Machut and Limburg, 2007In Hudson River watershed
-North CarolinaPresentIntroduced Invasive Moser et al., 2001
-Rhode IslandPresentIntroduced Invasive Aieta and Oliveira, 2009
-South CarolinaLocalisedIntroduced Invasive Fries et al., 1996
-TexasPresentIntroducedcirca 1995 Invasive Johnson et al., 1995First record in N. America


AustriaLocalisedIntroduced Invasive Schabuss et al., 2005Foci in stocked lakes
BelarusPresentIntroduced Invasive Moravec, 2006
BelgiumWidespreadIntroduced Invasive Schabuss et al., 1997First records 1980s
Czech RepublicWidespreadIntroduced Invasive Baruš et al., 1999aIntroduced with eel stocking
DenmarkWidespreadIntroduced Invasive Køie, 1991Introduced with eel stocking
EstoniaPresentIntroduced Invasive Höglund and Thomas, 1992
FranceWidespreadIntroduced Invasive Dupont and Petter, 1988Early introduction into south
GermanyWidespreadIntroduced Invasive Sures et al., 1999a; Neumann, 1985; Hartmann, 1987; Würtz et al., 1998First record from Europe in Weser-Ems in 1982. Now in all major rivers.
GreeceLocalisedIntroduced Invasive Moravec, 2006
HungaryLocalisedIntroduced Invasive Molnár, 1994Usually in stocked lakes, especially Lake Balaton
IrelandWidespreadIntroduced Invasive Evans and Matthews, 1999; Evans et al., 2001First report 1998, but now spreading rapidly. Introduced with eel trade
ItalyWidespreadIntroduced Invasive Canestri-Trotti, 1987; Koops and Hartmann, 1989Introduced with eels imported from France. Mainly in eel culture
MacedoniaPresentMoravec, 2006
NetherlandsWidespreadIntroduced Invasive Borgsteede et al., 1999First reported soon after arrival in Europe
NorwayLocalisedIntroduced Invasive Mellergaard, 1988Slower colonisation near limit of the species range
PolandWidespreadIntroduced Invasive Rolbiecki, 2008
PortugalWidespreadIntroduced Invasive Maíllo et al., 2005Often in coastal lagoons
Russian FederationPresentPresent based on regional distribution.
-Central RussiaLocalisedIntroduced Invasive Rodjuk and Shelenkova, 2006Mainly around Kaliningrad and Baltic Sea
SlovakiaLocalisedIntroduced Invasive Moravec, 2006In River Danube system
SpainLocalisedIntroduced Invasive Aguilar et al., 2005Localisation may reflect areas of study
SwedenLocalisedIntroduced Invasive Hellstrom et al., 1988; Höglund and Thomas, 1992Initially only in thermal effluents but now spreading more widely in south.
UKWidespreadIntroduced Invasive Kennedy and Fitch, 1990; Lyndon and Pieters, 2005Introduced with eel trade in south and east in 1987. Now widespread all over including Scotland.

History of Introduction and Spread

Top of page

A. crassus is the most efficient invasive helminth known (Nagasawa et al., 1994) but its rapid spread throughout the distribution range of the two species of Atlantic eel has been facilitated by, and is due in no small measure to, the uncontrolled inter-continental transfer of live eels. Its spread has, in fact, been so rapid that it has exceeded the rate at which it can be documented and any published account is invariably out of date. References cited in the table therefore tend to report the early stages of invasion as it is not possible to keep pace with the parasite’s subsequent spread throughout a country. It is already widespread throughout Europe (Ashworth and Blanc, 1997; Kirk, 2003; Moravec, 1992, 2006) and it can be predicted that its distribution range in Atlantic eels will become congruent with that of the eels themselves.

The first record of A. crassus outside the region of East Asia came from eels in the Weser-Ems system in North Germany in 1982 (Neumann, 1985). It is now almost certain that it arrived with a load of live eels imported into Bremerhaven from Taiwan (Koops and Hartmann, 1989). Thereafter the parasite spread rapidly, being recorded from the Ruhr Lake, Weser and Elbe estuary in 1986 (Moravec and Taraschewski, 1988) and subsequently spread to Berlin and the Rhine (Peters and Hartmann, 1986). In each locality its numbers increased rapidly after introduction: in the Elbe, for example, it was absent from eels in 1985, but by 1986 between 6 and 27% of eels were infected (Möller et al, 1991). As a consequence of further imports of live eels from East Asia as well as transfers of eels from different countries within Europe, A. crassus spread throughout the continent. On genetic grounds, Wielgoss et al. (2008) suggest that the path of colonisation has been from country to country from a localised source. There is no doubt at all that the rapidity of this spread was in large measure assisted by the uncontrolled inter- and intra-continental transfer of live eels. The re-stocking of lakes and rivers with eels, officially and unofficially, as well as providing eels for aquaculture ponds, promoted wide dispersal. In England, the first introduction of A. crassus was detected in 1987. By 1988 it was evident that it was dispersing from two foci in the east of the country, London and East Anglia, which were also the two main centres for the import of live eels (Kennedy and Fitch, 1990). Movements of eels around any country for re-stocking can disseminate the parasite even further (Belpaire et al., 1989; Koops and Hartmann, 1989).
The extraordinary rate at which A. crassus can spread throughout a continent is exemplified particularly well in North America. The first record of the species in the American continent came from an unidentified eel in an aquaculture facility in Texas (Johnson et al., 1995; Fries et al., 1996) and this again appears to be directly related to the importation of eels into the country. It has subsequently been found in wild populations of the American eel Anguilla rostrata and is still spreading rapidly northwards throughout the range of this host along the North Atlantic coast into Canada, having now reached as far as Cape Breton (Barse and Secor, 1999; Barse et al., 2001; Machut and Limberg, 2007; Aieta and Oliveira 2009; Rockwell et al., 2009). Thus, in only 13 years it has spread throughout the eastern seaboard, i.e. virtually the whole range of Anguilla rostrata. It is believed on genetic grounds that the parasite was imported directly into the USA from Japan (Wielgoss et al., 2008) rather than from Europe.
Recently A. crassus has been reported from species of African eels on Réunion Island in the Pacific Ocean. It is believed that it was introduced there in the course of eel imports rather than by natural movements of infected eels (Sasal et al. 2008).


Top of page
Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
Germany circa 1982 Aquaculture (pathway cause) Yes Koops and Hartmann (1989); Neumann (1985) First introduction in Europe, to Bremerhaven probably from Taiwan, imported with live eels
Italy France Aquaculture (pathway cause) Introduced with eel imports
Texas Asia   Aquaculture (pathway cause) Yes Wielgoss et al. (2008) From Asia, probably Japan, to Texas, N. America
UK 1987 Aquaculture (pathway cause) Introduced with eel imports

Risk of Introduction

Top of page

Although movements of eels for purposes of stocking and farming have played a major role in the rapid and widespread dissemination of A. crassus (Kennedy and Fitch, 1990; Belpaire et al., 1989) it is important to appreciate that A. crassus itself possesses many of the attributes of a successful coloniser (Kennedy and Fitch, 1990). These include: 1) a high reproductive potential, 2) a relatively simple life cycle with a low degree of specificity towards its intermediate host, including estuarine species of copepod, 3) the ability to use a wide range of fish species as paratenic hosts, 4) free living L2 larvae capable of surviving and remaining infective for long periods in freshwater of a range of salinities and in sea water, 5) the capability of infecting eels of all sizes, 6) the ability to survive for long periods in eels living in sea water, and 7) escaping the restrictions of a narrow specificity to its definitive host by using a species of fish that is itself widespread in distribution and capable of surviving a wide range of habitat and environmental conditions. It also occupies the swimbladder of an eel, a habitat in which there is no competitor. Every eel within the temperature and pH range of A. crassus is thus potentially at risk of infection. A combination of the colonisation abilities of the parasite, the natural movements of eels themselves and transfers of eels by man have enabled A. crassus to colonise Europe, North America and North Africa within 25 years: this is an extraordinary achievement.

Pathogen Characteristics

Top of page

A. crassus is, like all anguillicolids, parasitic as an adult in the lumen of the swimbladder of its eel host. Eels acquire infections by ingestion of an infected copepod, the intermediate host, or by ingestion of an infected fish, a paratenic host. In either case, the L3 larvae migrate to the swimbladder wall of the eel, where they moult to the L4 stage and eventually move into the lumen of the swimbladder and develop into adults. The adult is a large nematode with a stout body tapering at each end. It is a blood feeder with a well-developed buccal capsule, a row of circumoral teeth and a muscular oesophagus. The presence of blood and the breakdown products of blood in the intestine give the whole nematode a dark, almost black, appearance. The sexes are separate. The body wall and other organs are typical of nematodes in general. Males range in length from about 6-23 mm and in width from 0.3 to 1.8 mm, whilst females range from 13-45 mm in length and from 1.2 – 5.0 mm in width. Females in particular appear very robust. They are ovoviviparous: the uterus occupies most of the space of the body and contains eggs which in turn contain developing embryos and fully formed larvae (L2). A single female may contain up to 500,000 eggs (Kennedy and Fitch, 1990). The eggs may hatch inside the female to release the larvae, or may be shed from the female and hatch in the pneumatic duct so that the larvae pass out to the exterior with the eel faeces. Females die in the swim bladder, which then contains live worms of each sex as well as disintegrating parasite tissues and numerous eggs. The presence of adult parasites, both living and dead, brings about characteristic changes in the thickness of the swimbladder wall and affects the gas content and functioning of the swimbladder.

A. crassus can be distinguished from Anguillicola globiceps by the characteristic oesophagus of this latter species, which is conspicuously inflated at its anterior end, and from other species of Anguillicoloides by that fact that its cephalic end is not expanded and it lacks a distinct neck constriction (Moravec, 2006).

Hosts/Species Affected

Top of page
The only species deleteriously affected by A. crassus are the Atlantic eels, Anguilla anguilla and Anguilla rostrata. The parasite is harmless to Anguilla japonica and other species of Pacific eel. It appears that the parasite and Anguilla japonica may have co-evolved together such that this eel has acquired a measure of resistance to A. crassus (Egusa, 1979; Kim et al., 1989; Knopf and Lucius, 2008).

As far as is known, all individuals of Anguilla anguilla are equally at risk of infection by A. crassus: small individuals by eating infected copepods and large individuals by eating infected fish. There is no resistance to re-infection (Haenen et al., 1996) and antibodies produced against the parasite have no protective function (Knopf and Lucius, 2008). Once A. crassus has entered a lake or eel farm, its prevalence often rises to 100%, and transmission rates and infection levels may be very high when eel densities are themselves high as in eel farms or shallow lakes (Molnár et al., 1994; Baruš et al. 1999a). Stress in individual eel hosts may predispose them to disease (Gollock et al., 2005a).

Biology and Ecology

Top of page


The genetics of this species have been intensively studied, for more details see Heitlinger et al. (2009).



Top of page
C - Temperate/Mesothermal climate Preferred Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C
Cf - Warm temperate climate, wet all year Preferred Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)
D - Continental/Microthermal climate Tolerated Continental/Microthermal climate (Average temp. of coldest month < 0°C, mean warmest month > 10°C)

Notes on Natural Enemies

Top of page

There are no known natural enemies of A. crassus as such. There will always be some mortality of L2s through being eaten by copepods that are not suitable intermediate hosts and of L3s in paratenic hosts being eaten by fish other than eels or by birds, but there is no known predator or hyperparasite of adult parasites.

Impact Summary

Top of page
Fisheries / aquaculture Negative
Native fauna Negative
Other Negative

Economic Impact

Top of page
Despite many reports and references to the damage caused by A. crassus to Anguilla anguilla in eel farms in the Far East, especially in Japan, and to eels in Europe, there is little or no information actually published to quantify the damage in economic terms. Køie (1991), for example, refers to mortalities of 15-65% in a Dutch eel farm and increased mortalities from 10-20 % in other eel farms, but without placing any economic value on these losses.

In the cases of the eel mortalities attributed to A. crassus in European lakes, the only figures available relate to mortalities. Thus, Molnár et al. (1991, 1994) state that in 1991, 200 tonnes of eels died in Lake Balaton, and in 1992 40 tonnes. Baruš et al. (1999a) similarly quote a figure 3.5 tonnes of eels killed in the Vranov Dam in 1994, but no financial values have been attached to these losses. It must be presumed that there was a severe economic loss to professional eel fishermen as a consequence of the mortalities but no figures are available to support this presumption.
More recently, Taraschewski (2006) has made the point that as eel farming declines throughout Europe, even in Italy, in response to increasing energy and labour costs and as the price of ever scarcer elvers increases, A. crassus no longer poses so much of a threat and so will have a greatly reduced economic impact.

Environmental Impact

Top of page

Impact on biodiversity

The effects of A. crassus on wild eel populations are more difficult to study than those on captive ones, but experiments suggest that infected eels are more likely to die in adverse conditions (Didziulis, 2006). Mass mortalities have been reported among wild eels, but only when there have been particular combinations of unfavourable circumstances (for more details, see datasheet on Anguillicolosis). Concern has been expressed that severe damage to the swimbladder may reduce the ability of eels to migrate to their spawning grounds in the Sargasso Sea, which could have a severe impact on the future of the population (Didziulis, 2006). Such a decline could have significant effects on ecosystem community structure.

Threatened Species

Top of page
Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Anguilla anguilla (European eel)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered)Parasitism (incl. parasitoid); PathogenicPalstra et al., 2007; Sjöberg et al., 2009

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Fast growing
  • Has high reproductive potential
  • Has propagules that can remain viable for more than one year
Impact outcomes
  • Host damage
  • Negatively impacts aquaculture/fisheries
Impact mechanisms
  • Parasitism (incl. parasitoid)
  • Pathogenic
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Highly likely to be transported internationally illegally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control


Top of page

Aguilar A; Âlvarez MF; Leiro JM; Sanmartín ML, 2005. Parasite populations of the European eel (Anguilla anguilla L.) in the Rivers Ulla and Tea (Galicia, northwest Spain). Aquaculture, 249(1/4):85-94.

Aieta AE; Oliveira K, 2009. Distribution, prevalence, and intensity of the swim bladder parasite Anguillicola crassus in New England and eastern Canada. Diseases of Aquatic Organisms, 84(3):229-235.

Ashworth ST, 1994. Possible regulation in the Anguillicola crassus host-parasite system. In: Parasitic diseases of fish [ed. by Pike, A. W.\Lewis, J. W.]. Tresaith, Dyfed, UK: Samara Publishing, 141-150.

Ashworth ST; Blanc G, 1997. Anguillicola crassus, an aggressive coloniser recently introduced into European eel stocks. (Anguillicola crassus, un colonisateur agressif recemment introduit dans les stocks europeeans d'anguilles.) Bulletin Francais de Peche et Pisciculture, 1997:345-352.

Ashworth ST; Kennedy CR, 1999. Density-dependent effects on Anguillicola crassus (Nematoda) within its European eel definitive host. Parasitology, 118(3):289-296.

Ashworth ST; Kennedy CR; Blanc G, 1996. Density-dependent effects of Anguillicola crassus (Nematoda) within and on its copepod intermediate hosts. Parasitology, 113(3):303-309.

Bálint T; Ferenczy J; Kátai F; Kiss I; Kráczer L; Kufcsák O; Láng G; Polyhos C; Szabó I; Szegletes T; Nemcsók J, 1997. Similarities and differences between the massive eel (Anguilla anguilla L.) devastations that occurred in Lake Balaton in 1991 and 1995. Ecotoxicology and Environmental Safety, 37(1):17-23.

Barse AM; McGuire SA; Vinores MA; Eierman LE; Weeder JA, 2001. The swimbladder nematode Anguillicola crassus in American eels (Anguilla rostrata) from middle and upper regions of Chesapeake Bay. Journal of Parasitology, 87(6):1366-1370.

Barse AM; Secor DH, 1999. An exotic nematode parasite of the American eel. Fisheries (Bethesda), 24(2):6-10.

Baruš V; Krácmar S; Tenora F; Prokes M, 1998. Amino acid spectrum of uninfected and infected eels (Anguilla anguilla) by Anguillicola crassus (Nematoda). Folia Zoologica, 47(3):231-234.

Baruš V; Moravec F; Prokes M, 1999. Anguillicolosis of the European eel (Anguilla anguilla) in the Czech Republic. Czech Journal of Animal Science, 44(9):423-431.

Baruš V; Prokeš M, 1996. Length-weight relations of uninfected and infected eels (Anguilla anguilla) by Anguillicola crassus (Nematoda). Folia Zoologica, 45(2):183-189.

Baruš V; Tenora F; Krácmar S; Dvorácek J, 1999. Contents of several inorganic substances in European eel infected and uninfected by Anguillicola crassus (Nematoda). Diseases of Aquatic Organisms, 37(2):135-137.

Békési L; Hornok S; Székely C, 1997. Attempts to analyse Anguillicola crassus infection and the humoral host response in eels (Anguilla anguilla) of Lake Balaton, Hungary. Acta Veterinaria Hungarica, 45(4):439-445.

Belpaire C; Charleroy D de; Thomas K; Damme P van; Ollevier F, 1989. Effects of eel restocking on the distribution of the swimbladder nematode Anguillicola crassus in Flanders, Belgium. Journal of Applied Ichthyology, 5(3):151-153.

Boon JH; Augustijn H; Cannaerts VMH; Lokin CJA; Machiels MAM; Ollevier F, 1990. The suitability of experimental inoculations with infective larvae of Anguillicola crassus and their effects on the growth and mortality of the European eel (Anguilla anguilla). Aquaculture, 87(2):111-120.

Boon JH; Cannaerts VMH; Augustijn H; Machiels MAM; Charleroy D de; Ollevier F, 1990. The effects of different infection levels with infective larvae of Anguillicola crassus on haematological parameters of European eel (Anguilla anguilla). Aquaculture, 87:243-253.

Boon JH; Lokin CJA; Ceusters R; Ollevier F, 1989. Some properties of the blood of European eel (Anguilla anguilla) and the possible relationship with Anguillicola crassus infestations. Aquaculture, 76(3-4):203-208.

Borgsteede FHM; Haenen OLM; Bree J de; Lisitsina OI, 1999. Parasitic infections of European eel (Anguilla anguilla L.) in the Netherlands. Helminthologia, 36(4):251-260.

Buchmann K; Pedersen LO; Glamann J, 1991. Humoral immune response of European eel Anguilla anguilla to a major antigen in Anguillicola crassus (Nematoda). Diseases of Aquatic Organisms, 12(1):55-57.

Canestri-Trotti G, 1987. Occurrence of the nematode Anguillicola crassus Kuwahara, Niimi & Itagaki, 1974 in eels from the Po delta, Italy. Bulletin of the Association of Fish Pathologists, 7:109-111.

Cave D di; Berrilli F; Liberato C de; Orecchia P; Kennedy CR, 2001. Helminth communities in eels Anguilla anguilla from Adriatic coastal lagoons in Italy. Journal of Helminthology, 75(1):7-13.

Charleroy D de; Grisez L; Thomas K; Belpaire C; Ollevier F, 1990. The life cycle of Anguillicola crassus. Diseases of Aquatic Organisms, 8(2):77-84.

Didziulis V, 2006. NOBANIS-invasive alien species fact sheet - Anguillicola crassus. NOBANIS-invasive alien species fact sheet - Anguillicola crassus. 9 pp.

Dupont F; Petter AJ, 1988. Anguillicola, a multispecific epizootic in Europe. The appearance of Anguillicola crassa (Nematoda, Anguillicolidae) in the European eel, Anguilla anguilla, in Camargue, southern France. (Anguillicola, une épizootie plurispécifique en Europe. Apparition de Anguillicola crassa (Nematoda, Anguillicolidae) chez l'anguille Européenne Anguilla anguilla en Camargue, sud de la France.) Bulletin Français de la Pêche et de la Pisciculture, No. 308:38-41.

Egusa S, 1979. Notes on the culture of the European eel (Anguilla anguilla L.) in Japanese eel-farming ponds. Rapports et Proces-Verbaux des Reunions, Conseil Internationale pour l'Exploration de la Mer, 174:51-58.

Egusa S; Hirose H, 1983. Anguillicolosis of eels. In: Fish Pathology (Infectious diseases and parasitic diseases) [ed. by Egusa, S.]. Tokyo, Japan: Koseisha Koseikaku, 308-310.

Egusa S; Kira K; Wakabayashi H, 1969. On the occurrence of Anguillicola globiceps Yamaguti, a swimbladder roundworm, in pondcultured eels. Fish Pathology, 4:52-58.

Evans DW; Matthews MA, 1999. Anguillicola crassus (Nematoda, Dracunculoidea); first documented record of this swimbladder parasite of eels in Ireland. Journal of Fish Biology, 55(3):665-668.

Evans DW; Matthews MA; McClintock CA, 2001. The spread of the eel swimbladder nematode Anguillicola crassus through the Erne system, Ireland. Journal of Fish Biology, 59(5):1416-1420.

Fazio G; Moné H; Lecomte-Finiger R; Sasal P, 2008. Differential gene expression analysis in European eels (Anguilla anguilla, L. 1758) naturally infected by macroparasites. Journal of Parasitology, 94(3):571-577.

Fazio G; Sasal P; Silva C da; Fumet B; Boissier J; Lecompte-Finiger R; Mone H, 2008. Regulation of Angullicola crassus (Nematoda) infrapopulations in their definitive host, the European eels, Anguilla anguilla. Parasitology, 35(14):1707-1716.

Fontaine YA; Belle N le; Lopez E; Querat B; Vidal B; Barthelemy L; Sebert P; Alinat J; Petter AJ, 1990. Infestation of French populations of eels (Anguilla anguilla L.) by nematodes (Anguillicola crassus): therapeutic trials and evaluation of potential risks related to the ecophysiology of the host. (Infestation de populations françaises d'anguilles (Anguilla anguilla L.) par des nématodes (Anguillicola crassus): essais thérapeutiques évaluation de risques potentiels liés a l'écophysiologie de l'hôte.) Annales Parasitologiques Humaines et Comparees, 65:64-68.

Fries LT; Williams DJ; Johnson SK, 1996. Occurrence of Anguillicola crassus, an exotic parasitic swimbladder nematode of eels, in south-western United States. Transactions of the American Fisheries Society, 125:794-797.

Geets A; Liewes EW; Ollevier F, 1992. Efficacy of some anthelmintics against the swimbladder nematode Anguillicola crassus of eel Anguilla anguilla under saltwater conditions. Diseases of Aquatic Organisms, 13(2):123-128.

Genç E; Sahan A; Altun T; Cengizler I; Nevsat E, 2005. Occurrence of the swimbladder parasite Anguillicola crassus (Nematoda, Dracunculoidea) in European eels (Anguilla anguilla) in Ceyhan River, Turkey. Türk Veterinerlik ve Hayvancilik Dergisi, 29(3):661-663.

Gollock MJ; Kennedy CR; Brown JA, 2005. European eels, Anguilla anguilla (L.), infected with Anguillicola crassus exhibit a more pronounced stress response to severe hypoxia than uninfected eels. Journal of Fish Diseases, 28(7):429-436.

Gollock MJ; Kennedy CR; Brown JA, 2005. Physiological responses to acute temperature increase in European eels Anguilla anguilla infected with Anguillicola crassus. Diseases of Aquatic Organisms, 64(3):223-228.

Gollock MJ; Kennedy CR; Quabius ES; Brown JA, 2004. The effect of parasitism of European eels with the nematode, Anguillicola crassus on the impact of netting and aerial exposure. Aquaculture, 233(1/4):45-54.

Haenen OLM; Banning P van, 1990. Detection of larvae of Anguillicola crassus (an eel swimbladder nematode) in freshwater fish species. Aquaculture, 87(2):103-109.

Haenen OLM; Banning P van, 1991. Experimental transmission of Anguillicola crassus (Nematoda, Dracunculoidea) larvae from infected prey fish to the eel Anguilla anguilla. Aquaculture, 92(2-3):115-119.

Haenen OLM; Grisez L; Charleroy D de; Belpaire C; Ollevier F, 1989. Experimentally induced infections of European eel Anguilla anguilla with Anguillicola crassus (Nematoda, Dracunculoidea) and subsequent migration of larvae. Diseases of Aquatic Organisms, 7(2):97-101.

Haenen OLM; Wijngaarden TAM van; Heijden MHT van der; Höglund J; Cornelissen JBWJ; Leengoed LAMG van; Borgsteede FHM; Muiswinkel WB van, 1996. Effects of experimental infections with different doses of Anguillicola crassus (Nematoda, Dracunculoidea) on European eel (Anguilla anguilla). Aquaculture, 141(1/2):41-57.

Han YuSan; Chang YaTing; Taraschewski H; Chang SuLing; Chen CheChun; Tzeng WannNian, 2008. The swimbladder parasite Anguillicola crassus in native Japanese eels and exotic American eels in Taiwan. Zoological Studies, 47(6):667-675.

Hartmann F, 1989. Investigations on the effectiveness of levamisol as a medication against the eel parasite Anguillicola crassus (Nematoda). Diseases of Aquatic Organisms, 7(3):185-190.

Hartmann S, 1987. Swim bladder worms in the eel. (Schwimmblasenwürmer beim aal.) Fischer und Teichwirt, 38:2-3.

Heitlinger EG; Laetsch DR; Weclawski U; Han YuSan; Taraschewski H, 2009. Massive encapsulation of larval Anguillicoloides crassus in the intestinal wall of Japanese eels. Parasites and Vectors, 2(48):(15 October 2009).

Hellstrom A; Ljungberg O; Bornstein S, 1988. Anguillicola, a new eel parasite in Sweden. (Anguillicola, en ny alparasit i Sverige.) Svensk Veterinartiding, 40:211-213.

Höglund J; Andersson J; Wickström H; Reizenstein M, 1992. The distribution of Anguillicola in Sweden and its association with thermal discharge areas. Irish Fishery Investigations series A (Freshwater), 36:143-150.

Höglund J; Thomas K, 1992. The black goby Gobius niger as a potential paratenic host for the parasitic nematode Anguillicola crassus in a thermal effluent of the Baltic. Diseases of Aquatic Organisms, 13(3):175-180.

Johnson SK; Fries LT; Williams J; Huffman DG, 1995. Presence of the parasitic swimbladder nematode, Anguillicola crassus, in Texas aquaculture. Disease and Pathology, 26:35-36.

Kelly CE; Kennedy CR; Brown JA, 2000. Physiological status of wild European eels (Anguilla anguilla) infected with the parasitic nematode, Anguillicola crassus. Parasitology, 120(2):195-202.

Kennedy CR; Cave D di; Berrilli F; Orecchia P, 1997. Composition and structure of helminth communities in eels Anguilla anguilla from Italian coastal lagoons. Journal of Helminthology, 71(1):35-40.

Kennedy CR; Fitch DJ, 1990. Colonisation, larval survival and epidemiology of the nematode Anguillicola crassus, parasitic in the eel Anguilla anguilla, in Britain. Journal of Fish Biology, 36:117-131.

Kim YG; Kim EB; Kim JY; Chun SK, 1989. Studies on a nematode, Anguillicola crassa parasitic in the air bladder of the eel. Journal of Fish Pathology, 2:1-18.

Kirk RS, 2003. The impact of Anguillicola crassus on European eels. Fisheries Management and Ecology, 10(6):385-394.

Kirk RS; Kennedy CR; Lewis JW, 2000. Effect of salinity on hatching, survival and infectivity of Anguillicola crassus (Nematoda: Dracunculoidea) larvae. Diseases of Aquatic Organisms, 40(3):211-218.

Kirk RS; Lewis JW; Kennedy CR, 2000. Survival and transmission of Anguillicola crassus Kuwahara, Niimi & Itagaki, 1974 (Nematoda) in seawater eels. Parasitology, 120(3):289-295.

Kirk RS; Morritt D; Lewis JW; Kennedy CR, 2002. The osmotic relationship of the swimbladder nematode Anguillicola crassus with seawater eels. Parasitology, 124(3):339-347.

Knopf K, 2006. The swimbladder nematode Anguillicola crassus in the European eel Anguilla anguilla and the Japanese eels Anguilla japonica: differences in susceptibility and immunity between a recently colonised host and the original host. Journal of Helminthology, 80(2):129-136.

Knopf K; Lucius R, 2008. Vaccination of eels (Anguilla japonica and Anguilla anguilla) against Anguillicola crassus with irradiated L3. Parasitology, 135(5):633-640.

Knopf K; Mahnke M, 2004. Differences in susceptibility of the European eel (Anguilla anguilla) and the Japanese eel ( Anguilla japonica) to the swimbladder nematode Anguillicola crassus. Parasitology, 129:491-496.

Knopf K; Naser K; Heijden MHT van der; Taraschewski H, 2000. Evaluation of an ELISA and immunoblotting for studying the humoral imune response in Anguillicola crassus infected European eel (Anguilla anguilla). Diseases of Aquatic Organisms, 43:39-48.

Knopf K; Naser K; Heijden MHT van der; Taraschewski H, 2000. Humoral immune response of European eel Anguilla anguilla experimentally infected with Anguillicola crassus. Diseases of Aquatic Organisms, 42(1):61-69.

Knopf K; Würtz J; Sures B; Taraschewski H, 1998. Impact of low water temperature on the development of Anguillicola crassus in the final host Anguilla anguilla. Diseases of Aquatic Organisms, 33(2):143-149.

Koops H; Hartmann F, 1989. Anguillicola-infestations in Germany and in German eel imports. Journal of Applied Ichthyology, 5(1):41-45.

Kuwahara A; Niimi A; Itagaki A, 1974. Studies on a nematode parasitic in the air bladder of the eel I. Descriprion of Anguillicola crassus n.sp. (Philometridea, Anguillicolidae. Japanese Journal of Parasitology, 23(5):275-279.

Køie M, 1988. Parasites in eels, Anguilla anguilla (L), from eutrophic Lake Esrum (Denmark). Acta Parasitologica Polonica, 33:89-100.

Køie M, 1991. Swimbladder nematodes (Anguillicola spp.) and gill monogeneans (Pseudodactylogyrus spp.) parasitic on the European eel (Anguilla anguilla). Journal de la Conseil International pour Exploration de la Mer, 47:391-398.

Loukilli A; Belghyti D, 2007. The dynamics of the nematode Anguillicola crassus Kuwahara 1974 in eels Anguilla anguilla (L.1758) in the Sebou Estuary (Morocco). Parasitology Research, 100(4):683-686.

Lyndon AR; Pieters N, 2005. First record of the eel swimbladder parasite Anguillicola crassus (Nematoda) from Scotland. Bulletin of the European Association of Fish Pathologists, 25(2):82-85.

Maamouri F; Gargouri L; Ould Daddah M; Bouix G, 1999. Occurrence of Anguillicola crassus (Nematode, Anguillicolidae) in the Ichkeul Lake (Northern Tunisia). Bulletin of the European Association of Fish Pathologists, 19(1):17-19.

Machut LS; Limburg KE, 2007. Anguillicola crassus infection in Anguilla rostrata from small tributaries of the Hudson River watershed, New York, USA. Diseases of Aquatic Organisms, 79(1):37-45.

Maíllo PA; Vich MA; Salvadó H; Marqués A; Gracia MP, 2005. Parasites of Anguilla anguilla (L.) from three coastal lagoons of the River Ebro delta (Western Mediterranean). Acta Parasitologica, 50(2):156-160.

Mellergaard S, 1988. [English title not available]. (Alens swommeblaereorm Anguillicola - en ny parasit i den europaeiske alebestand.) Norges Aquaculture, 4:50-54.

Mohamed MH; Nouh M, 2004. Pathological studies on the swimbladder of Egyptian eels (Anguilla anguilla) infected with Anguillicola crassus. Assiut Veterinary Medical Journal, 50(102):212-227.

Molnár K, 1993. Effects of decreased oxygen content on eels (Anguilla anguilla) infected by Anguillicola crassus (Nematoda: Dracunculoidea). Acta Veterinaria Hungarica, 41:349-360.

Molnár K, 1994. Formation of parasitic nodules in the swimbladder and intestinal walls of the eel Anguilla anguilla due to infections with larval stages of Anguillicola crassus. Diseases of Aquatic Organisms, 20(3):163-170.

Molnár K; Baska F; Csaba G; Glávits R; Székely C, 1993. Pathological and histopathological studies of the swimbladder of eels Anguilla anguilla infected by Anguillicola crassus (Nematoda: Dracunculoidea). Diseases of Aquatic Organisms, 15(1):41-50.

Molnár K; Székely C; Baska F, 1991. Mass mortality of eel in Lake Balaton due to Anguillicola crassus infection. Bulletin of the European Association of Fish Pathologists, 11(6):211-212.

Molnár K; Székely C; Perényi M, 1994. Dynamics of Anguillicola crassus (Nematoda: Dracunculoidea) infection in eels of Lake Balaton, Hungary. Folia Parasitologica, 41(3):193-202.

Moravec F, 1992. Spreading of the nematode Anguillicola crassus (Dracunculoidea) among eel populations in Europe. Folia Parasitologica, 39(3):247-248.

Moravec F, 1994. Parasitic nematodes of freshwater fishes of Europe. Parasitic nematodes of freshwater fishes of Europe., 473 pp.

Moravec F, 1996. Aquatic invertebrates (snails) as new paratenic hosts of Anguillicola crassus (Nematoda: Dracunculoidea) and the role of paratenic hosts in the life cycle of this parasite. Diseases of Aquatic Organisms, 27(3):237-239.

Moravec F, 2006. Dracunculid and anguillicoloid nematodes parasitic in vertebrates. Praha, Czech Republic: Academia, 634 pp.

Moravec F; Cave D di; Orecchia P; Paggi L, 1993. Studies on the development of Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974 (Nematoda: Dracunculoidea) in the intermediate host. Folia Parasitologica, 40(1):39-48.

Moravec F; Cave D di; Orecchia P; Paggi L, 1994. Present occurrence of Anguillicola novaezelandiae (Nematoda: Drancunculoidea) in Europe and its development in the intermediate host. Folia Parasitologica, 41:203-208.

Moravec F; Di Cave D; Orecchia P; Paggi L, 1994. Experimental observations on the development of Anguillicola crassus (Nematoda: Dracunculoidea) in its definitive host, Anguilla anguilla (Pisces). Folia Parasitologica, 41(2):138-148.

Moravec F; Konecny R, 1994. Some new data on the intermediate and paratenic hosts of the nematode Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974 (Dracunculoidea), a swimbladder parasite of eels. Folia Parasitologica, 41(1):65-70.

Moravec F; Skoríková B, 1998. Amphibians and larvae of aquatic insects as new paratenic hosts of Anguillicola crassus (Nematoda: Dracunculoidea), a swimbladder parasite of eels. Diseases of Aquatic Organisms, 34(3):217-222.

Moravec F; Taraschewski H, 1988. Revision of the genus Anguillicola Yamaguti, 1935 (Nematoda: Anguillicolidae) of the swimbladder of eels, including descriptions of two new species A. novaezelandiae sp. n. and A. papernai sp. n. Folia Parasitologica, 35(2):125-146.

Moser ML; Patrick WS; Crutchfield JU Jr, 2001. Infection of American eels, Anguilla rostrata, by an introduced nematode parasite, Anguillicola crassus, in North Carolina. Copeia, No.3:848-853.

Münderle M; Sures B; Taraschewski H, 2004. Influence of Anguillicola crassus (Nematoda) and Ichthyophthirius multifiliis (Ciliophora) on swimming activity of European eel Anguilla anguilla. Diseases of Aquatic Organisms, 60(2):133-139.

Münderle M; Taraschewski H; Klar B; Chang CW; Shiao JC; Shen KN; He JT; Lin SH; Tzeng WN, 2006. Occurrence of Anguillicola crassus (Nematoda: Dracunculoidea) in Japnese eels Anguilla japonica from a river and an aquaculture unit in SW Taiwan. Diseases of Aquatic Organisms, 71:101-108.

Möller H; Holst S; Lüchtenberg H; Petersen F, 1991. Infection of eel Anguilla anguilla from the River Elbe estuary with two nematodes, Anguillicola crassus and Pseudoterranova decipiens. Diseases of Aquatic Organisms, 11(3):193-199.

Nagasawa K; Kim YG; Hirose H, 1994. Anguillicola crassus and A. globiceps (Nematoda: Dracunculoidea) parasitic in the swimbladder of eels (Anguilla japonica and A. anguilla) in East Asia: a review. Folia Parasitologica, 41(2):127-137.

Neumann W, 1985. The swim bladder parasite Anguillicola in eels. (Schwimmblasenparasit anguillicola bei aalen.) Fischer und Teichwirt, 11:322.

Nielsen ME, 1999. An enhanced humoral immune response against the swimbladder nematode, Anguillicola crassus, in the Japanese eel, Anguilla japonica, compared with the European eel, A. anguilla. Journal of Helminthology, 73(3):227-232.

Nimeth K; Zwerger P; Würtz J; Salvenmoser W; Pelster B, 2000. Infection of the glass-eel swimbladder with the nematode Anguillicola crassus. Parasitology, 121(1):75-83.

Norton J; Rollinson D; Lewis JW, 2005. Epidemiology of Anguillicola crassus in the European eel (Anguilla anguilla) from two rivers in southern England. Parasitology, 130(6):679-686.

Ooi HongKean; Wang WayShyan; Chang HongYou; Wu ChwenHerng; Lin ChengChung; Hsieh MengTong, 1996. An epizootic of anguillicolosis in cultured American eels in Taiwan. Journal of Aquatic Animal Health, 8(2):163-166.

Paggi L; Orecchia P; Minervini R; Mattiucci S, 1982. [English title not available]. (Sulla comparsa de Anguillicola australiensis Johnston and Mawson, 1940 (Dracunculoidea: Anguillicolidae) in Anguilla anguilla del Lago di Bracciano.) Parassitologia, 24:139-144.

Paliková M; Navrátil S, 2001. Occurrence of Anguillicola crassus in the water reservoir Koryeany (Czech Republic) and its influence on the health condition and haematological index of eels. Acta Vetinaria Brno, 70:443-449.

Palstra AP; Heppener DFM; Ginneken VJT van; Szekely C; Thillart GEEJM van den, 2007. Swimming performance of silver eels is severely impaired by the swimbladder parasite Anguillicola crassus. Journal of Experimental Marine Biology and Ecology, 352(1):244-256.

Pazooki J; Székely C, 1994. Survey of the paratenic hosts of Anguillicola crassus in Lake Velence, Hungary. Acta Veterinaria Hungarica, 42(1):87-96.

Peters G; Hartmann F, 1986. Anguillicola, a parasitic nematode of the swimbladder spreading among eel populations in Europe. Diseases of Aquatic Organisms, 1:229-230.

Pilcher MW; Moore JF, 1993. Distribution and prevalence of Anguillicola crassus in eels from the tidal Thames catchment. Journal of Fish Biology, 43:339-344.

Polzer M; Taraschewski H, 1993. Identification and characterisation of the proteolytic enzymes in the developmental stages of the eel-pathogenic nematode Anguillicola crassus. Parasitology Research, 79:24-27.

Reimer LW; Hildebrand A; Scharberth D; Walter U, 1994. Anguillicola crassus in the Baltic Sea: field data supporting transmission in brackish waters. Diseases of Aquatic Organisms, 18(1):77-79.

Rockwell LS; Jones KMM; Cone DK, 2009. First record of Anguillicoloides crassus (Nematoda) in American eels (Anguilla rostrata) in Canadian estuaries, Cape Breton, Nova Scotia. Journal of Parasitology, 95(2):483-486.

Rodjuk G; Shelenkova O, 2006. Parasite fauna of the European eel (Anguilla anguilla L, 1758) from the Russian part of the Vistula Lagoon (Baltic Sea). Wiadomosci Parazytologiczne, 52(2):121-125.

Rolbiecki L, 2008. New data on the introduced exotic nematode Anguillicola crassus Kuwahara, Niimi and Ikagaki, 1974 in the eel Anguilla anguilla in Lake Wdzydze (Polish waters). Oceanological and Hydrobiological Studies, 37(3):37-48.

Sasal P; Taraschewski H; Valade P; Grondin H; Wielgoss S; Moravec F, 2008. Parasite communities in eels of the Island of Reunion (Indian Ocean): a lesson in parasite introduction. Parasitology Research, 102(6):1343-1350.

Schabuss M; Kennedy CR; Konecny R; Grillitsch B; Reckendorfer W; Schiemer F; Herzig A, 2005. Dynamics and predicted decline of Anguillicola crassus infection in European eels, Anguilla anguilla, in Neusiedler See, Austria. Journal of Helminthology, 79(2):159-167.

Schabuss M; Konecny R; Belpaire C; Schiemer F, 1997. Endoparasitic helminths of the European eel, Anguilla anguilla, from four disconnected meanders from the rivers Leie and Scheldt in western Flanders, Belgium. Folia Parasitologica, 44(1):12-18.

Scholz F; Zerbst-Boroffka I, 1994. Osmotic and ionic regulation of the eel parasite Anguillicola crassus (Nematoda) and its host (Anguilla anguilla). (Osmo-und ionenregulation des aalparasiten Anguillicola crassus (Nematoda) und seines wirtes (Anguilla anguilla).) Zoologische Beitreagen, 35:103-117.

Sjöberg NB; Petersson E; Wickström H; Hansson S, 2009. Effects of the swimbladder parasite Anguillicola crassus on the migration of European silver eels Anguilla anguilla in the Baltic Sea. Journal of Fish Biology, 74(9):2158-2170.

Sprengel G; Lüchtenberg H, 1991. Infection by endoparasites reduces maximum swimming speed of European smelt Osmerus eperlanus and European eel Anguilla anguilla. Diseases of Aquatic Organisms, 11(1):31-35.

Sures B; Knopf K, 2004. Individual and combined effects of cadmium and 3,3’,4,4’,5-pentachlorobiphenyl (PCB 126) on the humoral immune response in European eel (Anguilla anguilla) experimentally infected with larvae of Anguillicola crassus (Nematoda). Parasitology, 128(4):445-454.

Sures B; Knopf K, 2004. Parasites as a threat to freshwater eels? Science, 304:205-206.

Sures B; Knopf K; Kloas W, 2001. Induction of stress by the swimbladder nematode Anguillicola crassus in European eels, Anguilla anguilla, after repeated experimental infection. Parasitology, 123(2):179-184.

Sures B; Knopf K; Taraschewski H, 1999. Development of Anguillicola crassus (Dracunculoidea, Anguillicolidae) in experimentally infected Balearic congers Ariosoma balearicum (Anguilloidea, Congridae). Diseases of Aquatic Organisms, 39(1):75-78.

Sures B; Knopf K; Würtz J; Hirt J, 1999. Richness and diversity of parasite communities in European eels Anguilla anguilla of the River Rhine, Germany, with special reference to helminth parasites. Parasitology, 119(3):323-330.

Sures B; Lutz I; Kloas W, 2006. Effects of infection with Anguillicola crassus and simultaneous exposure with Cd and 3,3’,4,4’,5-pentachlorobiphenyl (PCB 126) on the levels of cortisol and glucose in European eel (Anguilla anguilla). Parasitology, 132(2):281-288.

Székely C, 1994. Paratenic hosts for the parasitic nematode Anguillicola crassus in Lake Balaton, Hungary. Diseases of Aquatic Organisms, 18(1):11-20.

Székely C, 1996. Experimental studies on the infectivity of Anguillicola crassus third-stage larvae (Nematoda) from paratenic hosts. Folia Parasitologica, 43(4):305-311.

Székely C; Pazooki J; Molnár K, 1996. Host reaction in paratenic fish hosts against 3rd stage larvae of Anguillicola crassus. Diseases of Aquatic Organisms, 26(3):173-180.

Taraschewski H, 2006. Hosts and parasites as aliens. Journal of Helminthology [Environmental and ecological parasitology: the impact of global change. Proceedings of the Black Forest symposium, Freudenstadt, Germany, 7-10 April 2005.], 80(2):99-128.

Taraschewski H; Moravec F; Lamah T; Anders K, 1987. Distribution and morphology of two helminths recently introduced into European eel populations: Anguillicola crassus (Nematoda, Dracunculoidea) and Paratenuisentis ambiguus (Acanthocephala, Tenuisentidae). Diseases of Aquatic Organisms, 3(3):167-176.

Taraschewski H; Renner C; Mehlhorn H, 1988. Treatment of fish parasites 3. Effects of levamisole HCl, metrifonate, fenbenzadole, mebenzadole, and invermectin on Anguillicola crassus (nematodes) pathogenic in the air bladder of eels. Parasitology Research, 74:281-289.

Tesch FW, 1977. The eel: biology and management of anguillid eels. The eel: biology and management of anguillid eels., 434 pp.

Tesch FW, 1999. Der Aal, 3rd edn. Berlin: Parey Publisher.

Thomas K; Ollevier F, 1992. Paratenic hosts of the swimbladder nematode Anguillicola crassus. Diseases of Aquatic Organisms, 13(3):165-174.

Thomas K; Ollevier F, 1992. Population biology of Anguillicola crassus in the final host Anguilla anguilla. Diseases of Aquatic Organisms, 14(3):163-170.

Thomas K; Ollevier F, 1993. Hatching, survival, activity and penetration efficiency of second-stage larvae of Anguillicola crassus (Nematoda). Parasitology, 107(2):211-217.

Unger J; Brinker A; Stich HB, 2009. Transmission of neozoic Anguillicoloides crassus and established Camallanus lacustris in ruffe Gymnocephalus cernuus. Journal of Fish Biology, 73(9):2261-2273.

Wang P; Zhao Y, 1980. Observations on the life history of Anguillicola globiceps (Nematoda: Anguillicolidae). Acta Zoologica Sinica, 26:243-249.

Wielgoss S; Taraschewski H; Meyer A; Wirth T, 2008. Population structure of the parasitic nematode Anguillicola crassus, an invader of declining North Atlantic eel stocks. Molecular Ecology, 17(15):3478-3495.

Würtz J; Knopf K; Taraschewski H, 1998. Distribution and prevalence of Anguillicola crassus (Nematoda) in eels Anguilla anguilla of the rivers Rhine and Naab, Germany. Diseases of Aquatic Organisms, 32(2):137-143.

Würtz J; Taraschewski H, 2000. Histopathological changes in the swimbladder wall of the European eel Anguilla anguilla due to infection with Anguillicola crassus. Diseases of Aquatic Organisms, 39:121-134.

Würtz J; Taraschewski H; Pelster B, 1996. Changes in gas composition in the swimbladder of the European eel (Anguilla anguilla) infected with Anguillicola crassus (Nematoda). Parasitology, 112(2):233-238.

Zhang B, 1995. Studies on parasitic diseases in european eel (Anguilla anguilla) arms in Guangdong, China. In: Proceedings of the 10th Anniversary of the Founding of China Parasitological Society [ed. by China, Society of Parasitology of China]. 108-112.


Top of page

Denmark: North European and Baltic Network on Invasive Alien Species (NOBANIS), Web-based service,,


Top of page

04/10/09 Original text by:

Clive Kennedy, University of Exeter, School of Biosciences, Geoffrey Pope Building, Stocker Road, Exeter, EX4 4QD, UK

Distribution Maps

Top of page
You can pan and zoom the map
Save map