The use of silver nanoparticles (Ag-NPs) is rapidly increasing, but there are limited data on their effects on the aquatic environment. The present study aimed to determine the acute toxicity and evaluate the effect of subacute concentrations of Ag-NPs (Nanocid®: average particle size of 61 nm) on hematological and plasma biochemical indices of silver carp, Hypophthalmichthys molitrix, after 3, 7 and 14 days. The 24-, 48-, 72- and 96-h median lethal concentration (LC₅₀) values of Nanocid for silver carp were estimated at 0.810, 0.648, 0.383 and 0.202 mg/L, respectively; 20% and 10% of the 96-h LC₅₀ values (0.04 and 0.02 mg/L) were selected for subacute study. Red blood cell (RBC) count, hemoglobin (Hb) count and hematocrit (Hct) level were significantly reduced at both concentrations tested ( p < 0.05). White blood cell (WBC), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), cortisol and glucose levels in Nanocid-treated groups were significantly higher than the controlled group at experimental periods ( p < 0.05). In conclusion, Ag-NPs intoxication resulted in erythrocyte reduction, hematological disturbances, leucocytosis and stress response in silver carp and offered a simple tool to evaluate toxicity-derived alterations.