Evaluation of the toxic effect of peracetic acid on grass carp (Ctenopharyngodon idella) juveniles.

OBJECTIVES The aim of present study was to evaluate the effect of peracetic acid (PAA) on haematotological and biochemical indices, antioxidant status, micronucleus induction and histopathological alterations of liver and gill in grass carp. METHODS Grass carp (Ctenopharyngodon idella) juveniles were exposed to therapeutic concentrations (1, and 3 mg x l(-1)) of PAA for a period of 10 days. Selected haematotological indices--the erythrocyte count (RBC), haematocrit (PCV), haemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and leukocyte count (WBC), and biochemical indices--glucose (Glu), total protein (TP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), and lactate dehydrogenase (LDH) were evaluated in plasma. Activity of superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR), as well as levels of thiobarbituric acid reactive substances (TBARS) were assessed in gill and liver. Micronucleus frequency in peripheral erythrocytes was counted in control and experimental fish. Histological examinations of gill and liver were performed. RESULTS No significant differences were found in haematological parameters measured. Statistically significant (p < 0.05) alterations in the activities of AST, CK and LDH were found in treated fish compared to control groups. Fish exposed to 1 mg x l(-1) of PAA showed significantly lower (p < 0.05) SOD activity in liver and gill while catalase activity indicated a significant decrease (p < 0.05) only in gill tissue. Other significant changes were observed in GR activity in gill in both PAA exposed groups, while GR activity in liver remained unchanged. There was no significant difference in the count of micronuclei between control and exposed fish. Haemorrhage, fusion of primary lamellae, degeneration of secondary lamellae, some clubbing on primary and secondary lamellae tips, and lifting of epithelial cells were found in gill tissues in both control and treated fish. CONCLUSION The results show that PAA could induce alterations in biochemical parameters in blood plasma, antioxidant enzymes response and histopathological changes in gill; however, it seems that these changes are reversible. Subsequently, lower concentration (1 mg x l(-1)) is useable as a treatment concentration for grass carp.