The Algerian freshwater fish fauna is mainly represented by the Cyprinidae family, in particular, the genus m>Barbusm>. This is represented only by natural populations of the subgenus m>Barbusm>. The systematic, based mainly on the methods of biometrics, is quite different from one author to another. However, two nominal species are usually cited: m>Barbus callensism> (Valenciennes, 1842), which is limited to the region of El Kala (eastern Algeria) and m>Barbus setivimensism> (Valenciennes, 1842) in other parts of the North. During the ecological study of this fauna, many individuals were found infested with the tapeworm m>Ligula intestinalism> (Linn茅, 1758), which led us to study the effect of this parasite on m>B.m>聽m>setivimensism> using the ecological parasites鈥?index (prevalence, abundance and parasite intensity) and to focus on the impact of the parasite on the growth of fish. Tapeworm m>L.m>聽m>intestinalism> presents a wide geographical distribution and a complex lifecycle to multiple hosts: the cycle starts in the body of birds. The life expectancy in the major host is a maximum of 5 days, but in this time, they will lay a multitude of eggs. These eggs are passed into water via the faeces of the bird. Once in the aquatic medium, they hatch and are eaten by a wide range of copepod zooplankton (first intermediate host). The cycle continues when fish (second intermediate host) ingests the copepod. The worm then burrows through the gut wall and continues to develop in the fish's body cavity. The cycle is then complete when the bird (final host) eats the tapeworm-hosting fish. We studied the effects of diet, the hosting period, the habitat on the prevalence, abundance and intensity of the parasitic larvae plerocercoid m>L.m>聽m>intestinalism> and the parasiting effect on the Cyprinids fishs of the genus m>Barbusm> in the Keddara dam (Boumerdes, Algeria) during one year. Although m>Lm>.聽m>intestinalism> was recorded in several host fish, the available data on the parameters of parasitism are limited and no studies are reported on m>B.m>聽m>setivimensism>. In this study, a total of 613 individuals were sampled and checked on the presence of m>L.m>聽m>intestinalism> plerocercoid stages. Only 64 were infested. The value of the prevalence was 10.44%and the average intensity was 1.89 parasites (average two parasites per infested fish). The infection rate is high during the autumn and low during the spring season. The latter corresponds with the breeding period.
