The influence of molecular ammonia on erythrocyte osmotic fragility in grass carp fingerlings.

The effects of various concentrations(0.2,0.5,and 1.0 mg/L)of molecular ammonia and different exposure periods(24,72,120,168,and 264 h)on erythrocyte osmotic fragility(EOF)were studied in grass carp(Ctenopharyngodon idellus)fingerlings.The EOF was found to increase extremely in the experiment groups,with significant maximum and minimum resistance value compared to the control group(P0.01).There was the maximal increase in EOF in the group at the molecular ammonia concentrations of 1.0 mg/L,significant difference compared to the 0.2 mg/L group and 0.5 mg/L groups(P0.01).The EOF was found to increase gradually with the prolongation of exposure time within 168 h,the maximum and minimum resistance value occurring between 24 h and 72 h,between 72 h and 120 h,and between 120 and 168 h,without change in the EOF in the control group during the experiment.After 168 h,the EOF increased slowly,no significant difference in the maximum and minimum resistance value between 168 h and 264 h(P0.05).There was significant difference in the maximum and minimum resistance value between 264 h and 120 h(P0.01),indicating that molecular ammonia may lead to the increase in erythrocyte osmotic fragility in grass carp fingerlings via concentration-time dependence.