BACKGROUND: Diazinon is an organophosphate pesticide which is widely used in paddy fields located in northern parts of Iran, though it is prohibited to be used in many countries. OBJECTIVES: The purpose of the present study was to investigate sublethal effects of diazinon on blood parameters of common bream Abramis brama. METHODS: In sublethal toxicity test, fish were exposed to diazinon concentrations of 0.04, 0.36, 0.73 and 1.46 mg/l for 14 days and their hematological parameters including WBCs, white cell differential count, RBCs, Hct, Hb, MCV, MCH and MCHC were studied.  RESULTS: The results of sublethal toxicity indicated that by increase of toxicant concentration a significant decrease was appeared in WBCs, RBCs, Hct, Hb and MCH both after 7 and 14 days (p<0.05). After 7 days a significant decrease was observed in lymphocytes count which accounted for about %81 of the control group. The neutrophils count was also face the same reduction so that after 14 days of diazinon exposure, the neutrophils counted decreased to about %85 of control group. CONCLUSIONS: Regarding the toxicity of diazinon on various hematological parameters and the diazinon concentration in Iranian waters and considering the fish habitat in the waters which are connected to the Caspian Sea it suggests that the pesticide diazinon affect the fish survival.

Introduction: The study examined the concentration of total mercury and correlation coefficients between fish size or FCF (condition factor) and the content of Hg in muscle tissue of six freshwater fish: bream (Abramis brama L.), roach (Rutilus rutilus L.), whitefish (Coregonus lavaretus L.), vendace (Coregonus albula L.), perch (Perca fluviatilis L.), and pike (Esox lucius L.). Material and Methods: The fish were caught from the Lake Pluszne located in the Olsztyn Lake District (Poland). Mercury was analysed by atomic absorption spectrometry using Milestone DMA-80 (with dual-cell). Results: The content of the element in the muscles of the examined fish was as follows: pike (0.197 mg/kg) ≈ perch (0.173 mg/kg) > vendace (0.114 mg/kg) ≈ roach (0.095 mg/kg) and roach ≈ whitefish (0.065 mg/kg), and whitefish ≈ bream (0.042 mg/kg) (p ≤ 0.05). In all cases, the content of mercury correlated positively with the body weight and total length of the fish. Only the correlation coefficients between mercury concentration and weight or length of bream were slightly higher (0.979 and 0.977 respectively, p ≤ 0.001). The length and weight relationship of the fish was also determined. Conclusion: The results showed that the levels of mercury were lower than the maximum acceptable limit established by the Commission Regulation (EC) No 629/2008 of 2 July 2008. Thus, they are safe from consumer health point of view.