Occurrence of parasites, length-weight relationship and condition factor of Sarotherodon melanotheron (Ruppel, 1852) in Ilaje Local Government Area of Ondo State, Nigeria

Abstract. Fish parasites immensely affect fish production given their potential impact on profitability and also cause of zoonotic diseases in many parts of the world. This study therefore investigated the effect of fish parasites on growth and well-being. It also evaluated the body variation between parasitized and non- parasitized fish. The study was carried out in five rivers from Ipare, Aboto, Alape, Igbanran and Igbokoda. The length of parasitized fish samples was 13.00±1.26cm, 14.02±1.94cm and 13.51±1.67cm in male, female and combined sexes, respectively, while the weight was 43.29±12.51g, 53.86±21.52g and 48.57±17.92g in male, female and combined sexes, respectively. Also, the average total length (TL) of the non-parasitized fish was 12.92±1.13cm, 14.72±1.53cm and 13.67±1.57cm in male, female and combined sexes, respectively, while the weight was 38.86±9.33g, 62.09±16.50g and 48.49±17.12g in male, female and combined sexes, respectively. The regression coefficient (b) of length and weight of parasitized samples was b=2.12 (male), b=2.15 (female) and b=2.64 (combined sexes), while the regression coefficient ‘b’ recorded for the length-weight relationship of non-parasitized samples was 3.25, 2.49 and 2.78 for male, female and combined sexes, respectively, indicating allometric growth. Also, Senga sp and Nematodes were the most prevalent parasites with average volume of 2.33±0.58 and 2.00±0.00 on both male and female fish, respectively. The regression analysis revealed that the occurrence of parasites did not have significant effect (P>0.05) on the length and weight of S. melanotheron from Ilaje Local Government Area of Ondo State, Nigeria. This study also established similarity in morphology among populations of male and female as well as parasitized and non-parasitized Sarotherodon melanotheron from the study area.