We studied the changes in the serum COR,GLU,LDH,TC,AST,ALT and CREA,as well as the respiratory rate of grass carp at 0 h,0.5 h,1 h,6 h and 24 h after the grass carp passed the jet fish pump under 4 operating conditions.In comparison to the fish who didn’t pass the jet fish pump,fish who passed the pump under the 4 operating conditions showed an increase in the serum COR,CREA,LDH,AST and ALT as well as the respiratory rate at the first recovery period and then those values decreased to control values gradually,while the serum GLU showed a decline after an initial increase.There was no significant difference in the serum TC in the present study.In addition,the descaling was observed in grass carp under the 4 operating conditions.When fish passed the jet fish pump under the 4 operation conditions,there were no rupture of swimming bladder and damage of viscera.Among the 4 operating conditions,the third operating condition showed less influence on grass carp than the other operating conditions.