New data on the biology of the introduced exotic nematode Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974 in the eel Anguilla anguilla in Lake Wdzydze (Polish waters)

Anguillicola crassus Kuwahara, Niimi et Itagaki, 1974 is an Asian parasitic nematode that was introduced to Europe and inhabits the swim bladder of eels. In the 2002-2005 period, 237 eels, Anguilla anguilla (Linnaeus, 1758), from Lake Wdzydze were examined for the occurrence of the nematode. 79.3% of the fish were infected, at a mean intensity of 7.2 nematodes per fish. Morphological measurements of the observed A. crassus are presented. This is the first published report of A. crassus in eels from Lake Wdzydze.