Impact of Pollution on Haematology and Histology of Juveniles of Chrysichthys nigrodigitatus in Ogbese River, Ondo State, Nigeria

The silver catfish Chrysichthys nigrodigitatus is of economic importance in sub-sahara Africa. In Ogbese town, and its environs, it constitutes a means of income and food for fisherfolks and community members. Hence, this study was undertaken to assess health status of Chrysichthys nigrodigitatus using haematology and histological assessment of the fish specie due to the anthropogenic activities that takes place around the river body. A total 120 live juvenile fish samples of C. nigrodigitatus were collected around shallow habitats of Ogbese River by the assistance of fisherfolks using fish cage. Some water parameters measurements were taken: temperature, pH, DO, Turbidity and Conductivity. Morphometric measurement: Weight (g) and length (cm) of fish were taken. Haematology and histology of fish gills, liver and intestine were determined. Mean water temperature (27.70±0.18°C), pH (7.36±0.22), DO (6.98±0.15 mg/l), Turbidity (78.50±13.53 NTU) and Conductivity (148.35±27.98) of the river determined respectively. Mean body weight of fish was 148.15 ± 36.53 g, and mean length was 25.64 ± 2.86 cm. The gills, liver and intestines of the fish specie were examined to assess the architecture of the organs. Results of haematology studies of C. nigrodigitatus revealed high values in the parameters measured. Red Blood Cell was higher than the White Blood Cell with mean value of (225.63±10.45 103/mm3) while Eosinophils recorded lowest parameters with mean value of (1.75±0.52%). Results of histology of gills, liver and intestines showed that the gill filaments were eroded with deformation of the cartilage core and also hyperplasia of the secondary lamellae. The intestines showed atrophy in a mucosal layer, hemorrhage and dilation within blood vessels and within serosa of mucosa and for liver, picnotic nucleus were shattered, the hepatocytes were ruptured and there was increased kupffer cell count as a result of exposure to pollutants. The results indicated that pollution level of the environment have significant impact on health status of fish.