The European Eel Anguilla anguilla (Anguillidae) Invasion by the Allochthone Nematode Anguillicoloïdes crassus in Southern Mediterranean

For the first time, the spreading of a fearsome non-native parasite nematode Anguillicoloïdes crassus is studied in European Eel Anguilla anguilla in 4 different coastal ecosystems throughout 12 years. We found that the parasite become more abundant with time in each study site; only 4.8% of eels inhabited brackish water (Mellah Lagoon) are infected while—over the third of fish are infected in the other waterbodies parasite nematode is presented in fish of all ages as well as of both sex; however infected specimens are less common among juveniles and males Based on the evaluation of the swimbladder degenerative index, we found that swimbladder is damaged in more than a half of fish captured in freshwater, however the opposite situation is observed in the brackish water.There is a significant difference in age, length, weight and condition between infected and uninfected fish.