The response of plasma glucose, lactate, protein and hematological parameters to osmotic challenge in common carp (Cyprinuscarpio)

Fluctuations in salinity impose stress on the physiology of the exposed fish population and can modify their structure. It has been noted that changes in blood characteristics and plasma levels serve as the primary link between environmental change and physiological response (McCormick, 2001). Ninety healthy adult Cyprinuscarpio (C. carpio) were randomly divided into five groups and kept in salinities of 1 (control group), 3, 6, 9, 12 and 15 g/L The salinity was gradually increased by 3 g/L daily to final their concentrations. Fish were kept for 14 days after transference to the final salinity. Subsequently, plasma glucose, lactate, and protein content, as well as hematological parameters, were evaluated. The highest hematocrit (Hct), hemogloblin level (Hb), red blood cell count (RBC), lactate, and glucose values were found fish kept in the highest salinity. The values of the white blood cell count (WBC) showed an initial increase in fish from the control group until a salinity of 9 g/L, but subsequently decreased at higher salinities. The plasma protein levels among the fish in different groups did not show a significant change. The results demonstrate that changes in blood parameters can be used as indices to monitor the effects of salinity on the physiology of C. carpio.