Effects of temperature and pH on the digestive enzymes activities of juvenile striped beakperch Oplegnathus fasciatus

The effects of temperature and pH on digestive enzymes activities (stomach, intestine and liver) were investigated in juvenile striped beakperch Oplegnathus fasciatus. The results indicated that the optimum temperature for protease in intes- tine and liver was 25℃, and that in stomach was 28℃. The optimum temperature for amylase in stomach and liver was 22℃, and that in intestine was 19℃. The optimum temperature for lipase in three digestive organs was all 16℃. During 16℃ to 28℃, the protease and lipase both had relatively high activities, however, the amylase had a lower activity. The optimum pH values for protease, amylase and lipase were 3.2, 7.6 and 4.2 in stomach, and 8.6, 6.6 and 6.6 in intestine, respectively. The optimum pH in liver was 7.6 for protease, and 6.6 for amylase and lipase.