Investigation of interactive effect of salinity and ammonia poisoning on some hematology factors and antioxidant capacities in oxidative stress reactions of tilapia (Oreochromis niloticus)

The present study was designed to investigate the interaction effect of acute and subacute ammonia toxication in different salinity levels (0, 4, 8 and 12 g/l) on some hematological factors and oxidative enzymes in Nile tilapia (Oreochromis niloticus). To investigate the interactions, 360 fish (57.32±16.7 g) were randomly divided into 12 treatment groups (each with three replicates). At the end of the experiment (96 hour), hemoglobin, hematocrit, red blood cell count, catalase (CAT), superoxide dismutase (SOD) and glutathione (GSH) were measured. According to the results, LC50- 96 hours of NH3 was 0.86 mg/l. The results showed that hematocrit, hemoglobin, glutathione, superoxide dismutase and catalase decreased in treatment of acute ammonia poisoning and 0 salinity and treatment of subacute poisoning and 0 salinity compared to treatment 1 (control) (P<0.05). The results showed that increasing salinity levels in treatments improved catalase and superoxide dismutase levels. In general, the results indicate that ammonia poisoning maybe by producing free radicals has weakened the antioxidant system of fish. Also ammonia toxicity effects were decreased with increasing water salinity, which reduced oxidative stress enzymes.