The increasing use of nano based-product induces the potential hazards from their manufacture, transportation, waste disposal and management processes. The Ag-NPs were synthesized using chemical reduction method and the formation of Ag-NPs was monitored by Uv-visible spectroscopy analysis. Functional crystalline nature and morphological characterization were carried out by Fourier transform infrared spectroscopy (FTIR) and high resolution transmission electron microscope (TEM) analysis. This project work was extended to determine the potential acute toxicity of Clarias gariepinus exposed to lethal concentration (LC50) of Ag-NPs. The fresh water fish, Clarias gariepinus 10 per concentration were exposed to each of the lethal concentrations (750, 850, 900 and 1000µg/ml) of Ag-NPs for 24hrs, 48hrs, 72hrs and 96hrs. Also, C. gariepinus were exposed to sub-lethal concentrations (5, 10, 50 and 100μg/ml) of Ag-NPs and Ag-salt for a period of 42 days.
Acute behavioural response of LC50 of C.gariepinus exposed to different concentrations (750, 850, 900 and 1000µg/ml) of Ag-NPs exhibited distress responses due to the introduction of Ag-NPs, behavioural changes were erratic swimming, gasping for breath, loss of reflex, discoloration, moulting, haemorrhagic and anaemic appearances which worsen as Ag-NPs concentration increases. As hours of exposure increased, fish were getting weaker, having their ventral surface turned upward while those that could not tolerate the concentrations went into a state of motionlessness before death. Though, normal behaviours were observed in the control treatment. The freshwater fish, C. gariepinus (25) were exposed to each of the sub-lethal concentrations (5, 10, 50 and 100μg/ml) of Ag-NPs and Ag-salt for a period of 42 days. Blood samples were taken on 14th, 28th and 42th days for the haematological analysis. The haematological analysis revealed a significant reduction (P<0.05) in Red Blood Cells count from 2.66×106 in the control fish to 1.34×106 of highest concentration of Ag-salt and also there was a significant decreased (P< 0.05) from the control value of 2.66×106 to 1.36×106 of highest concentration of Ag-NPs. This is due to the lysis of red blood cell. WBC values decreased from the control value of 14.94×104 to 6.06×104 of highest concentration of Ag-salt, and also decreased from the control value of 14.94×104 to 2.96×104 of highest concentration of Ag-NPs. The result obtained in PCV and HB values revealed a significant increased (P> 0.05) in the Ag-salt and Ag-NPs in respect to concentrations and exposure time when compared with the control. This is an indication of polycythemia which result into erythropoiesis. The mean values of MCV, MCH and MCHC increased significantly (P>0.05) in the fish exposed to Ag-salt and Ag-NPs when compared with the control. This is an indication of macrocyte anaemia. It is obvious from this study that higher concentrations of Ag-salt and Ag-NPs negatively affect haematology of fish, causing various disturbances in its health and wellbeing.