A quantitative study of some digestive enzymes in the rabbitfish, Siganus canaliculatus and the sea bass, Lates calcarifer

Digestive enzyme distribution and activity in the digestive tracts of the rabbitfish, Siganus canaliculatus and the sea bass, Lates calcarifer were studied. Quantitative determinations of digestive enzymes in the guts of both fishes showed that they were capable of digesting carbohydrates and proteins in their diet. The carbohydrases, amylase, laminarinase, maltase, sucrase and trehalase were detected in the rabbitfish; their activities being mainly in the stomach, intestine and pyloriccaeca. Amylase, maltase, trehalase and chitinase activities were recorded in the gut of the sea bass, primarily in the intestine and the pyloriccaeca. Their activities were significantly lower than those in the rabbitfish. Proteases (pepsin, chymotrypsin, elastase, leucine aminopeptidase and trypsin) were found in both the rabbitfish and the sea bass. Pepsin activity however, was higher in the sea bass; while trypsin and chymotrypsin activities were higher in the rabbitfish. The activities of the various digestive enzymes in both fishes are discussed in relation to their feeding habits.