Haematological Indices of African Catfish (<i>Clarias gariepinus</i>) Juvenile Exposed to DDVP (Dichlorvos) Insecticide

Abstract

This study investigated the impact of DDVP (Dichlorvos) insecticide on the hematological indices and mortality rates of juvenile Clarias gariepinus exposed to various concentrations of DDVP. Juvenile African catfish were procured and acclimated for two weeks in dechlorinated water under natural conditions. A total of 150 fish were randomly allocated into five treatment groups (T1-T5) in triplicate, each containing 10 fishes, and exposed to various concentrations of DDVP based on a 96-hour LC50 of 0.00056 ml/L. The experimental groups included T1 (control, 0.00000 ml/L), T2 (0.000112 ml/L), T3 (0.000224 ml/L), T4 (0.000336 ml/L), and T5 (0.000448 ml/L). Temperature and pH of experimental water were monitored daily. Fish mortality was assessed at multiple time points throughout the experiment, with dead fish removed promptly to prevent oxygen depletion. Hematological analysis was performed by collecting blood samples through caudal ablation. Results showed that mortality rates were significantly higher in the highest concentrations (T4: 85.00 ± 7.07% and T5: 100.00 ± 0.00%) compared to lower concentrations (T1: 0.00 ± 0.00%, T2: 15.00 ± 7.07%, T3: 20.00 ± 14.14%) (p < 0.05). T5 exhibited the highest mortality rate among all treatments. Hematological analysis revealed significant alterations in the blood parameters of C. gariepinus exposed to DDVP. The packed cell volume (PCV) was notably reduced in the T3 group (20.33%) compared to other groups, suggesting adverse effects on erythropoiesis. The red blood cell (RBC) count was lowest in T2 (2.00 ± 0.00 × 10^6/L), correlating with decreased PCV, indicating potential anaemia or reduced red blood cell production. The white blood cell (WBC) count was markedly increased in T2 (4.03 ± 0.06 × 10^9/L), suggesting an inflammatory or stress response. This study highlights the detrimental effects of DDVP on the health and blood parameters of Catfish, with higher concentrations leading to increased mortality and significant hematological disturbances.