the relationship between water salinity and ec with heamatocrite, blood serum ionic parameters, growth, survival and stress indices in common carp (cyprinus carpio linneaus 1758)

this study was carried out within 7 months in dikjeh area, golestan province, iran. during that time the relationship between water salinity and ec with hematocrite, blood serum ionic parameters, growth, survival and stress indices in common carp (cyprinus carpio) were investigated. hematocrite as stress index was measured by hemocitometry standard method using microhematocrite reader. fish biology assay characteristics such as length, weight, condition factor and growth rate in every month were determined. common carp with average weight of 45 g was abandoned and after 7 months average gaining weight reached to 705 g. the range of salinity (0.3-2.7 ppt), ec (843-5230 µm/cm2), na+ (43.59-408.7 mmol/l), k+ (0.90-9.21 mmol/l), ca2+ (2.69-18.29 mg/dl) and mg2+ (0.80-10.88 mg/dl) were measured. according to the pierson, water ec with length, weight and mg2+ of blood serum and biomass of fish had positive correlation but with condition factor and ca2+ of blood serum had negative correlation. water salinity with length, weight, biomass of fish and mg2+ of blood serum and with k+ of blood serum showed positive correlation. but survival and blood hematocrite had not significant correlation with this range of water salinity and ec. as a result, common carp in this range of water salinity (0.3-2.7 g/l) and ec (843-5230 µm/cm2) without stress has a suitable growth and because of isoosmotical status with environment and less energy expenditure, has a higher growth.