Chesapeake Bay Introduced Species Database

Anguillicoloides crassus

Common name(s):
Eel Swimbladder Nematode
The Eel Swimbladder Nematode is native to Japan and coastal China, where it is a widespread and common parasite of the Japanese Eel (Anguilla japonica). In the 1980s it was found in European Eel (Anguilla anguilla) in Germany, where it was likely transported with shipments of live Japanese Eels. From this early introduction and many secondary introductions, the parasite spread all across Europe. The parasite was first discovered in North America at an aquaculture facility in south Texas, but soon was seen in many other areas including the Chesapeake Bay. In the Chesapeake Bay ballast water is a likely vector for transport of this parasite because copepods, the nematode?s most frequent intermediate host, have been seen in samples of ballast water about to be discharged into the Bay. Eels get the nematode by eating copepods and other crustaceans that have eaten the parasite. When the nematode larvae are eaten by the eel, they make their way to the eel?s swimbladder where they grow into reproducing adults. Adult nematodes release their larvae into the swimbladder. The larvae leave through the pneumatic duct into the water where they can again be eaten by copepods. American Eels (Anguilla rostrata) in some areas of the Bay have high infection rates, but given the eel?s migratory lifestyle, it?s difficult to know if this plays a role in there declining population.
Image courtesy of Bill Bessmer, Wiki Commons.


Anguillicoloides crassus


Anguillicola crassus

Potentially Misidentified As:

Anguillicola globiceps; Anguillicola novazealandiae

Common Names:

Eel Swimbladder Nematode


Potentially misidentified species- 5 species of Anguillicoloides are known; A. globiceps and A. crassus are native to eastern Asia, while A. australiensis is native to Australia, A. papernai to southern Africa, and A. novaezelandiae to New Zealand. A. crassus and A. novaezelandiae have both been recorded from Anguilla anguilla the European Eel (in Italy), but A. crassus is much more widespread and is the only species recorded from North America. (Koie 1991; Barse et al. 2001).

This data was last modified on Friday, January 10th, 2014.
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