Changes in some Haematological Parameters of the African Catfish ( Clarias gariepinus ) Exposed to a Metal Finishing Company Effluent

Abstract

Metal company effluent toxicity in Clarias gariepinus , was investigated by the hematological parameters after long-term (8 weeks) exposure to various effluent sub-lethal concentrations (3.5397, 7.0794 and 14.1589ml/L effluent). Test groups were set up in duplicates for each concentration, plus the control group. Blood samples were collected from four individuals bi-weekly for each concentration at 0, 2, 4, 6, and 8 th weeks of exposure. Most of the investigated physico-chemical characteristics of the effluent showed deviation from the FEPA (1991) limits. The effluent caused a mean decrease of haematocrit (30.02 ± 1.21% to 24.75 ± 4.57%), haemoglobin (10.02 ± 0..95g/100ml to 8.60 ± 1.34g/100ml), mean corpuscular haemoglobin (74.00 ± 8.64pg/cell to 30.45 ±12.75Pg/cell). Erythrocytes increased from 135.08 ± 10.55 to 367.42 ± 94.88 and then decreased to 219.07 ± 48.66 × 103 cells/mm 3 . Leucocytes also followed a similar pattern. The MCV and MCH also varied significantly (P > 0.05). The leucocytes peak (103.0 × 10 3 cells/mm 3 ) was recorded in week 4, in fish from the highest concentration tank. The study suggested that the metalfinishing effluent has strong influence on the hematological parameters in C.gariepinus .