The efficacy of fenbendazole against tapeworm infections in the common carp (Cyprinus carpio L.) in Veľké Blahovo ponds

A survey of the pond system in Veľké Blahovo, Dunajská Streda district, Slovak Republic, confirmed the occurrence of tapeworms in carp with a prevalence of 63.5% and mean intensity of 1.7 ± 2.72. The species Khawia sinensis and Atractolytocestus huronensis were identified. We attempted to reduce the occurrence of tapeworms using a medicated feed mixture (granules) with 1% fenbendazole as active substance under controlled conditions. Faeces collected from carp (K2) were examined and the presence of tapeworm eggs was confirmed by the flotation method. Positive carp were divided into three groups; each group, labelled F1 to F3, included 15 individuals. The carp were placed in concrete pools (storage ponds) nourished by fish pond water at the peak of the vegetation period from August 7-17, 2015. The medicated feed mixture was administered to the first two groups (F1 and F2), while the third group was fed with a non-medicated feed mixture and served as the control (F3). A single dose was administered to the F1 group; tapeworm prevalence 24 hours after administration in the F1 group was 26.66% with a mean intensity of 1.3 ± 0.57. The F2 group was fed three times in total with 24-hour intervals between feeding. Tapeworm prevalence 24 hours after the last administration in the F2 group was 13.33% with a mean intensity of 2.0 ± 0.77. The prevalence in the control group was 66.66% with a mean intensity of 2.2 ± 1.62. Khawia sinensis tapeworms responded well to fenbendazole, while A. huronensis tapeworms responded poorly and, despite repeated administration of the active substance, this species remained attached to the intestinal mucosa. When compared with the control group, the reduction in the number of tapeworms was statistically significant (P ≤ 0.05) in the F2 group; however, it was not statistically significant in the F1 group.