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Keywords:

larvae, 06 Biological Sciences, 07 Agricultural and Veterinary Sciences, Fisheries

Abstract:

Six anthelmintic drugs, Ivermectin, Closantel, Safewormer, Masoten, Oxfendazole and L-Levamisol . HCl, were screened for their efficacy against Anguillicola crassus, a swimbladder nematode of European eel Anguilla anguilla. All experiments were carried out under saltwater conditions. Of the 6 drugs, L-Levamisole . HCl used in a bath treatment gave the most promising results. Evaluation of the curative dose of L-Levamisole . HCl showed that a long-term treatment (6 d) with 20 mg l-1 was far more effective than a short-term treatment (24 h). Dosages lower than 20 mg l-1 showed a lower efficacy against Anguillicola crassus. However, even with a long-term, high-dosage treatment, some recovery of adult nematodes with sublethal damage and/or migration of viable juveniles into the swimbladder lumen could not be excluded. When examined 35 d after treatment, the percentage of mobile adults had increased, while a decrease in percentage of dead worms was noticed compared to values obtained immediately after treatment.