This study was done to determine the activity of digestive enzymes amylase, lipase and alkaline phosphatase in 5 parts of the gastrointestinal tract ofLiza abu, and Johniusbelangeriithat havenutritional and economic importance in the southern area of Iran.10 fish of both species with mean weight 150 ± 10grcaught in Musa creek of Persian Gulf were selected.After preparation of the samples and performing all the routine measurement of enzymeusingautoanalyzer model CA- 400, resultsshowed thatamylase, alkaline phosphatase and lipase enzymes activity were significant difference between the two species.So that in the beginning of intestine the amylase activity was upper compared to the middle and end of intestine (p<0.05).It was very high for alkaline phosphatase activity in Liza abu, compare toJohniusbelangerii in all areas (25000 to 3000).Lipase activity showed significant differences as contrary to amylase and alkaline phosphatase activity in fish like Liza abu, compare to Johniusbelangerii(p<0.05). The results showed that these differences could be due to the type of food used by fish as Liza abufollows the pattern of phytoplankton and Johniusbelangeriifollows carnivorous diet.