Abstract: Study on haematological responses of Sarotherodon melanotheron transferred directly from brackish water (salinity 120/00) to fresh water of (0.130/00), was carried out to asses the magnitude of the effect of sudden change in environment on fish haematology. The results indicated significant reduction (p< 0.05) in mean values of heamoglobin from 5.51�0.51; to 3.95�0.49 g dL 1; haematocrit 19.88�0.90 to 17.07�0.87%; leucocrit 6.74�0.54 to Red blood cells 2.48�0.06 to 1.89�0.12 Platelets 169.53�8.84 to 107.52�9.68%; Lymphocytes 41.97�1.61 to 36.57�0.92% and mean corpuscular haemoglobin concentration 27.57�2.28 to 24.51�2.50 g dL 1. However, increment was recorded in the value of White Blood Cell from 29.42�0.88 to 31.37�0.80 x 109/l; mean morpuscular volume 78.33�3.96 to 79.78�5.80. mean corpuscular haemoglobin 21.64�1.94 to 29.94�2.21pg: neutrophil 35.53�1.62 to 41.32�1.27% and monocytes 2.31�0.16 to 3.10�0.13. These variations in the blood parameters were more pronounced in male than female fish. Results from this study suggest that change in the salinity of the environment may impact negatively on the physiology of S. melanotheron as demonstrated in changes in the blood characteristics.
U.U. Gabriel , P.E. Anyanwu and A.O. Akinrotimi , 2007. Effect of Freshwater Challenge on the Blood Characteristics of Sarotherodon melanotheron. Agricultural Journal, 2: 388-391.