The types of digestive enzymes were analyzed in digestive tracts of common carp Cyprinus carpio silver carp Hypophthalmichthys rnolitrix, bigheand carp A ristichthys mobilis, grass carp Ctenopharyngodon idellus by polyacrylamide gel electrophoresis, and the relative activities of the digestive enzymes were determined in the fishes by colorimetry and titration.The results showed that the order of the protease activity was arranged as common carp 〉silver carp 〉 bighead carp 〉 grass carp, and that for amylase activity as grass carp 〉 bighead carp 〉common carp 〉silver carp. The digestive enzyme expression in these fishes was found to be paralleled to the histology structure of digestive tracts. The maximal digestive enzymic activity was observed in the 2/5 parts in anterior end of the digestive tract （G1, G2）, where was found to be the main place for digestion in those stomachless fishes, followed by the following 1/5 part of digestive tract （G3）. The minimal digestive enzymic activity was occurred in the last 2/5 parts （G4, G5） of the intestines. The findings provide a theoretical basis for the nutritional physiology, the development of feedstuff and the management for germplasm in these fisheries.%采用聚丙烯酰胺凝胶电泳方法研究了鲤、鲢、鳙、草鱼亲鱼消化道消化酶的种类；用比色法及滴定法分别测其消化酶相对活性。结果表明：鲤、鲢、鳙、草鱼4种鱼消化道的蛋白酶、淀粉酶活性与食性有明显的相关性。其中，蛋白酶活性依次为鲤〉鲢〉鳙〉草鱼；淀粉酶活性依次为草鱼〉鲤〉鳙〉鲢。脂肪酶活性与食性的关系不明显。四种鱼消化酶的表达与消化道的组织结构特征相一致，消化道前2／5部位（G1、G2）的消化酶活性最高，是无胃鱼消化道的主要消化场所。消化道中央部位（G3）的消化酶活性次之，能将未消化完全的食糜进一步消化，而消化道后段（
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