The digestive tube index and the activity distribution of three kinds of digestive enzymes in the digestive organs of cultured Siganus canaliculatus

The digestive tube index and the activity distributions of three kinds of digestive enzymes in the digestive organs of cultured Siganus canaliculatus (average body weight of 58.51 g± 21.15 g and body length of 13.08 cm±1.856 cm) were studied in the paper. With a normal method, the digestive tube indices of S.canaliculatus were measured. The ratio of intestine gut length to body length was 2.595±0.457 while the ratios of viscera, liver, stomach, pyloric caecum and intestine weight to body weight were 0.157 2±0.023 0, 0.016 6±0.006 0, 0.011 5±0.007 0, 0.004 3±0.002 1 and 0.020 2±0.010 2, respectively. The exponential regression equation of body weight and body length was Y=0.080 6X2.545 7(r=0.977 7,P0.01). The specific activity of protease in different organs was in the order of pyloric caecum intestine liver stomach, while amylase in the order of intestine pyloric caecum stomach liver, and lipase in the order of pyloric caecumliverintestinestomach. The total protease activity, amylase activity and lipase activity in intestine were much higher than that in other digestive organs, respectively. The A/P values of liver, stomach, intestine, pyloric caecum were 2.15, 22.65, 3.81, 1.96 respectively. The result showed that the intestine was the most important functional organ for digestion and S. canaliculatus was a kind of polyphagia fish that leaned to be herbivorous based on the digestive tube indices, the activity distributions of three kinds of digestive enzymes and A/P values.