Activity of peptidases and glycosidases of the digestive tract in some species of bony fish of Vietnam

For the first time, the activity and pH dependence of digestive enzymes were studied in fish inhabiting the Mekong Delta: duskyfin glassy perchlet Parambassis wolffii, smallscale croaker Boesemania microlepis, catfish Pangasius macronema, and representatives of the family Cyprinidae. Significant interspecific differences were revealed in the level of peptidase and glycosidase activity providing hydrolysis of protein and carbohydrate food components. The greatest interspecific differences are characteristic of glycosidases: the level of enzymatic activity in Cyprinidae fish exceeds that in P. wolffii by 13.6 times. The differences in the level of peptidase activity in fish of different species are lower: in the case of the activity of stomach enzymes in P. wolffii, the values are 1.8 times higher than those in P. macronema, and in the case of total activity of stomach and intestinal enzymes in the same species, the values are 1.5 times higher. The data obtained confirm the concept that the digestive hydrolase activity depends on the fish feeding spectrum. The activity of intestinal enzymes decreases more significantly in the acidic pH zone than in the basic one. Consequently, acidification of the intestinal environment will negatively affect the digestive processes in these fish species.