Distribution of gill Monogenean parasites from Oreochromis niloticus (Linn, 1758) in man-made Lake Ayam I, Cte dIvoire

A parasite study was conducted from August 2004 to July 2005 to highlight the distribution of gill Monogenean parasites from Oreochromis niloticus. A total of 370 fish collected from Ayame man-made Lake, Cote d’Ivoire were examined for Monogenean species using routine parasitological techniques. The study revealed the presence of six species of Monogeneans (Cichlidogyrus thurstonae, Cichlidogyrus halli, Cichlidogyrus tilapiae, Cichlidogyrus rognoni, Cichlidogyrus cirratus and Scutogyrus longicornis). These species showed an aggregate pattern within the host population. Four species of parasites showed positive and significant correlation with parasitic abundance and the relative condition factor. The prevalence and intensity of the infection of these parasites were highest in the long rainy season and lowest in the dry season. The large sized fishes were more subjected to parasitic infection than smaller ones. In contrast, no sex effect was observed on the infestation of O. niloticus by the Monogeneans. No preference for the right or left side of the fish host was observed and the parasite species mostly colonized the middle arches (II and III). This could lead to more informed aquacultural practises, and maximization of the production of O. niloticus. Key words: Disease, season, sex, infestation, gill.