Complete name: Anguillicola crassus Kuwahara, Niimi & Itagaki 1974
Taxonomy: Nematoda » Nematoda » Secernentea » Spirurida » Anguillicolidae » Anguillicola crassus
Authors: Dan Minchin
Last updated: January 7th, 2008

Eel swim-bladder nematode.

Anguillicola crassus

This is a parasite nematode often 3cm in length that can only be noticed by opening up the body cavity of the freshwater eel. It has a large girth and a transparent outer skin that allows the inner organs to be seen.

• Dispersal Mechanisms
  • By movements of its various hosts and water currents.
• Reproduction
  • It occurs as an adult in the freshwater eel Anguilla anguilla and matures after 8-10 months, but in two months at 20°C. Present in eels throughout the year. Adult eels may contain > 70 nematodes and each eel can contain 500,000 eggs laid in the swim bladder. These and newly hatched larvae pass through the pneumatic duct to the gut and are expelled with faeces.
• Known Predators/Herbivores
  • Larvae are consumed by planktonic crustaceans, amphipods and isopods to develop in their haemocoel and in turn are consumed by glass eels. Other fishes, amphibians and larval insects can act as paratenic hosts should they feed on infected crustacea. If eaten by an eel the nematode burrows through the stomach wall to lodge on the air bladder and moults to the adult stage.
• Resistant Stages (seeds, spores etc.)
  • None.

• Native (EUNIS Code)
  • Endoparasite: Occurs in the Japanese eel Anguilla japonicus.
• Habitat Occupied in Invaded Range (EUNIS Code)
  • Endoparasite: Intermediate host in arthropods and has its final stage in the European eel A. anguilla and the American eel A. rostrata.
• Habitat Requirements
  • Larval stages normally occur in freshwater but can tolerate 8% salinity. May occur in hosts in marine conditions.

Aquaculture. Imports of infected eels for culture or spread by paratenic (transfer) hosts, from exchanges of water containing eggs and larval stages. Larvae may be distributed in crustaceans released by ships’ ballast water.

• Native Range
  • Eastern Asia, from China to Vietnam, Taiwan, Japan
• Known Introduced Range
  • Europe and eastern North America.
• Trend
  • Spreading.

known distribution area (in CGRS grid squares; in countries; along coast)

	eradicated
	extinct
	not present; eradicated
	native distribution range in CGRS grid squares
	native range
	assumed native range
	infrequent distribution
	key distribution area
	not established

• Ecosystem Impact
  • Adult nematodes feed on blood supplied to the swimbladder wall and can result in eel mortality. Nematodes may contribute to the decline of the North Atlantic eel stock because eels may not reach spawning areas due to damaged swimbladders.
• Health and Social Impact
  • Infected eels may be more susceptible to stresses following damage to the air bladder, spleen and liver. No human impacts.
• Economic Impact
  • May compromise eel-culture production and may contribute to a decline in fishery landings. The International Council for the Exploration of the Sea presently advise a discontinuation of the fishery.

• Prevention
  • Stock transfers of fish from infested areas should be controlled. No live imports of infested eels should be permitted to islands.
• Mechanical
  • Filtration and treatment of water used for culturing eels.
• Chemical
  • None.
• Biological
  • None.

The following contributors have provided records in the DAISIE database for this species.

The following experts registered themselves as having knowledge about this species or its family.

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Kennedy CR, Fitch DJ (1990) Colonisation, larval survival and epidemiology of the nematode Anguillicola crassus, parasite in the eel Anguilla anguilla in Britain. J Fish Biol 36:117-131

Lefebvre F, Mounaix B, Poizat G, Crivelli AJ (2004) Impacts on the swimbladder nematode Anguillicola crassus on Anguilla anguilla: variations in liver and spleen mass. J Fish Biol 64:435-447

Moravec F, Škoríková B (1998) Amphibians and larvae of aquatic insects as new paratenic hosts of Anguillicola crassus (Nematoda: Dracunculoidea) a swimbladder parasite of eels. Dis Aquat Org 34: 217-222

Belpaire C, De Charleroy D, Thomas K, van Damme P, Ollevier F (1989) Effects of eel restocking on the distribution of the nematode Anguillicola crassus in Flanders, Belgium. J Appl Ecol 5:151- 153

De Charleroy D Grisez L, Thomas K, Belpaire C, Ollevier F (1990) The life cycle of Anguillicola crassus. Dis Aquat Org 8:77-84

De Nie HW (1987) Food, feeding periodicity and consumption of the eel Anguilla anguilla L. In the shallow eutrophic tjeukemeer (The Netherlands). Arch Hydrobiol 109:421-443

Fries LT, Williams DJ (1996) Occurence of Anguillicola crassus, an exotic parasitic swim bladder nematode of eels, in the southeastern United States. Trans Am Fish Soc 125:794-797

Haenen OLM, Van Banning P, Dekker W (1994) Infection of eel Anguilla anguilla (L.) and smelt Osmerus eperlanus (L.) with Anguillicola crassus (Nematoda, Dracunculoidea) in the Netherlands from 1986 to 1992. Aquaculture 126:219-229

Hirose H, Sekino T, Egusa S (1976) Notes on the egg deposition, larval migration and intermediate host of the nematode Anguillicola crassus parasitic in the swimbladders of eels. Fish Pathol 11:27-31

Johnson SK, Fries LT, Williams J, Huffman DG (1995) Presence of the parasitic swim-bladder nematode, Anguillicola crassus, in Texas aquaculture. World Aquaculture 26:35-36

Kennedy CR (1993) Introductions, spread and colonization of new localities by fish helminth and crustacean parasites in the British Isles: a perspective and appraisal. J Fish Biol 43:287-301

Koops H, Hartmann F (1989) Anguillicola infestations in Germany and in German eel imports. J Appl Ichthyol 1:41-45

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. Dis Aquat Org 27:237-239

Peters G, Hartmann F (1986) Anguillicola, a parasitic nematode of the swim bladder spreading among eel populations in Europe. Dis Aquat Org 1:229-230

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). Dis Aquat Org 3:167-176

Thomas K, Ollevier F (1992) Paratenic hosts of the swimbladder nematode Anguillicola crassus. Dis Aquat Org 13:165-174