Abstract:The distributions of nonspecific esterase, acid phosphatase and alkaline phosphatase in digestive tract of Tilapia Galilaea (Oreochromis niloticus ♀ × O. aureus ♂) were studied by paraffin section combined with histochemical methods including Gomori’s staining and acid-α-naphthyl-acetate esterase staining. It was found that nonspecific esterase densely distributed in the foregut, massively distributed in the stomach, esophagus and midgut, and slightly distributed in the hindgut (Fig. 1). Acid phosphatase mainly distributed in the foregut, followed by the midgut and stomach, and few in the esophagus and hindgut (Fig. 2). Alkaline phosphatase was densely observed in the foregut and midgut, and a larger amount was also observed in the stomach, esophagus and hindgut (Fig. 3). The results showed that the foregut, midgut, esophagus and stomach of Tilapia Galilaea were the main sites of lipid absorption and digestion. The foregut, midgut and stomach were the main sites of protein absorption and digestion, and the foregut and midgut were the main sites of nutrient absorption.