Evaluation of the sub-lethal effects of silver nitrate (AgNO3) concentration toxicity on some hematology and immunology indices in goldfish (Carassius auratus)

Among metal pollutants silver ions are the most toxic forms, and have been assigned to the highest toxicity class. Today, due to the antibacterial properties of silver compounds they are used in various industries. The effects of non-essential heavy metals such as silver are irreversible on aquatic animals’ body. In the present study, the sub-ethal effects of silver nitrate on hematology and Immunology parameters of goldfish (Carassius auratus) as a model species in Cyprinidae family were investigated.
105 fish werer randomly placed in 15 fiberglass tanks (400 liters); 12 tanks were used for different concentrations of silver nitrate and 3 tanks were used for control groups. The fishe of each treatment were separately exposed to effective silver nitrate concentrations of 0.01, 0.025, 0.05 and 0.1 ppm, and for hematological and biochemical test, nine fish were randomly selected from each treatment. Measured indices were total number of white blood cells (leukocytes), lymphocytes, neutrophils, eosinophil, total number of red blood cells (erythrocytes), hemoglobin content, hematocrit level, mean corpuscular volume (MCV), hemoglobin the corpuscular (MCH), hemoglobin concentration and serum glucoses.
The results showed that different concentrations of silver nitrate influenced blood erythrocyte (P>0.05) but did not affect blood leukocyte, which may be due to the resistance of the gold fish compared to others. Blood could be introduced as a suitable biomarker of silver pollution.