Consequences of Direct Transfer to Fresh Water on the Blood Variables of Sarotherodon melanotheron (Rüppell, 1852)

Alterations in blood variables of Sarotherodon melanotheron transmitted immediately from brackish water (salinity 13.71‰) to fresh water (salinity 0.12‰) were examined to evaluate the consequence of abrupt alterations in the environment on fish blood parameters. The results acquired revealed that significant reduction (p < 0.05) in mean values of Haemoglobin (Hb) from 7.37±1.22 to 4.30±0.82dl-1; Packed Cell Volume (PCV) 23.48±3.22 to 15.08±2.97%; Red Blood Cell (RBC) 5.99±0.72 to 3.31±0.77 Cells x106 ; Mean Corpuscular Haemoglobin Concentration (MCHC) 31.68±3.66 to 28.48±2.03 pg; and Platelets (PLT) 195.44±16.77 to 138.99±9.05 103 uL-1. However, notable elevation was recorded in the values of Erythrocyte Sedimentation Rate (ESR) from 4.89±0.16 to 10.58±1.48 mm/ hr; White Blood Cell (WBC) 27.03±2.96 to 33.09±3.72 x 109 L-1; Mean Corpuscular Volume (MCV) 39.33±3.07 to 45.88±7.03 fL Neutrophils (NEUT) 41.71±3.08 to 48.30±7.99%; Lymphocytes (LYMP) 54.60±3.99 to 46.36±9.87% and Monocytes (MON) 3.80±1.04 to 5.97±1.99%. These variations in the blood parameters were more perceptible in adult than juvenile fish. Results from this study consequently imply that direct transfer of fish to a region of lower salinity may have damaging effect on the physiology of S. melanotheron as observed in this study