摘要Objective: To investigate the possible effects of silver nanoparticles (AgNPs) on some blood and plasma indices of rainbow trout (Oncorhynchus mykiss). <br> Methods: Hence, fish were exposed for 21 days to sub-lethal concentrations of colloidal AgNPs and blood parameters including erythrocyte size and hematocrit, plasma parameters including cholinesterase, cortisol, sodium, chloride, and potassium, and also silver concentration in plasma were measured following the 11th and 21st days of exposure. <br> Results:According to the results of present study, higher concentrations of AgNPs had more significant effects on plasma biochemistry and hematology of trout. The greatest impacts were decline of chloride ions and increase of cortisol and cholinesterase. Also fish exposed to AgNPs significantly increased silver concentration in the plasma. <br> Conclusions:Further studies are needed to identify appropriate blood biomarkers following fish exposed to nanomaterials, especially AgNPs.