*Silurus meridionalis*)

*n*=48］胃内容物的湿重和干重。研究结果表明,随摄食后时间的延长,胃内容物的湿重和干重均显著下降(

*P*<0.01),二者的摄食量百分比也具类似的变化特征(

*P*<0.01);三种数学模型均能较好地拟合胃内容物重量的变化过程,但三者之间在以相关系数(

*R*

^{2})、残差平方和(

*RSS*)及残差的标准差(

*SDR*)为标准仍存在明显差异。用平方根模型对南方鲇幼鱼胃内容物湿重和干重数据的拟合结果最优,其方程分别为

*Y*

^{0.5}=1.889-0.051×

*t*(

*R*

^{2}=0.87,

*P*<0.001)和

*Y*

^{0.5}=0.870-0.024×t(

*R*

^{2}=0.86,

*P*<0.001);南方鲇幼鱼在25 ℃下的胃排空率为0.051 g/h,其99%胃排空时间为36.7 h,该种鱼近99%胃排空时间的实测值为餐后36 h,这与最优数学模型的计算结果较为接近;南方鲇与鲇具有类似的胃排空特征和相同的最优数学排空模型。

*Silurus meridionalis*),forty eight experimental fish［(58.45±1.66) g,(19.4±0.2) cm］were fed individually with a loach meal［(3.33±0.09) g］equivalent to 6%(5.8%±0.2%)of the catfish’s body mass,and removed from the various intervals(0,2,4,8,16,24,36,48 h)after feeding at 25 ℃.The wet and dry mass of the chyme were determined and the applicability of three mathematical models was compared by the good of fitness fitted to gastric evacuation data in juvenile southern catfish.The results of present study showed that:the wet and dry mass of remaining food in stomach as well as percentage of food residual decreased profoundly as postprandial time increased;Though three mathematical models all fitted well the gastric evacuation data,there still were several significant differences among these regression results.As mentioned above,it suggested that the best mathematical model fitted to gastric evacuation data in juvenile southern catfish was the squareroot model and its regression equations for wet mass and dry mass of the chyme mass were

*Y*

^{0.5}=1.889-0.051×

*t*(

*R*

^{2}=0.87,

*P*<0.001)and

*Y*

^{0.5}=0.870-0.024×

*t*(

*R*

^{2}=0.86,

*P*<0.001),respectively;The gastric evacuation rate of

*S.meridionalis*was among the range of 0.051 g/h,and the 99% of gastric evacuation time was among the range of 36.7 h which was similar to the actual measurement values(36 h)in the present study;The juvenile southern catfish and Chinese catfish possess the similar gastric evacuation characters and the optimum mathematical model was the squareroot model.

*Silurus meridionalis*; gastric evacuation rate; mathematical model; digestion physiology