Studies on digestive enzymes in alimentary tract of southern sheatfish (Silurus meridionalis Chen) larvae I—Trypsin and pepsin

The pepsin and trypsin activities and some of the properties of the two enzymes of southern sheatfish larvae were studied. The results were as follows: the highest level of trypsin activity is in the foregut in all measured tissues; from foregut to hindgut, trypsin activities decrease; the pH optimum of trypsin activity is pH9.0; the strongest pepsin activity is in the stomach; the proper density of haemoglobin for detecting pepsin activity is 1.0%. These data are useful in solving applied nutritional problems, such as the adequacy of artificial food to the digestive abilities of the fish.