Variations in Digestive Enzymes Activities in Tongue Fish Cynoglossus semilaevis Larvae and Juveniles

The varitions in activities of main digestive enzymes (acid protease,alkaline protease,amylase and lipase) and alkaline phasphatase in different development stages of tongue fish Cynoglossus semilaevis were determined.It is shown from the determined results that the activities of acid protease and alkaline protease in tongue fish can be detected in the early larval development stage,two extreme low alkaline protease activities were observed during the period of the first feeding and the transition from larva to juve-(nile),and the activity of acid protease increased obviously from the appearance of gastric gland(about the 23rd day after hatch).The noticeable amylase activity was exhibited in the early larval stage,the activity decreased drastically from the twelfth day after hatch,and then kept at a low specific activity level.The lipase activity kept at a low level in the early larval stage and then increased slowly after entering the juve-(nile) stage.After the metamorphosis was completed,the alkaline phosphatase activity increased rapidly,which indicates the maturity of enterocytes and the improvement of digestive mechanism of intestines.