ABSTRACT
Clarias albopunctatus juvenile (mean weight 85.40±2.67 g) was exposed to sublethal concentrations of Ronstar (0, 0.2, 0.6 and 1.2 mg/l) in a static renewal bioassay system for 15 days. The hematological parameters of the fish were determined every 5 days. When compared with the control, the erythrocyte count (RBC), hemoglobin (Hb) and the hematocrit (Hct) were significantly reduced (P<.05) between the treatment groups. These values also differed (P<.05) within the treatment groups. The leucocyte counts increased with increasing Ronstar concentration and during the exposure. Compared with the control, significant (P<05) lymphocytosis, monocytopenia, neutropenia and reduced eosinophil were all evident in the treatment groups. The reduction in the erythrocyte count and hemoglobin are indications of anemia in the fish exposed to Ronstar. The assay of these parameters could be of immense value in establishing safe limits for pesticides in Nigerian waters as well as in the monitoring of fish health.