Activity of intestinal mucosal brush border membrane enzymes in relation to the feeding habits of three aquaculture fish species

The activity of intestinal mucosal enzymes in various parts of the intestine and the pyloric caeca of adult fish from three different species was examined. Selection of the fish for the study was based on their aquacultural importance and the different feeding habits they exhibit: carnivorous hybrid striped bass (Morone saxatilisxMorone chrysops); omnivorous tilapia (Oreochromis niloticusxOreochromis aureus) hybrids and herbivorous silver carp (Hypophthalmichthys molitrix). The results show marked differences among the different fish species corresponding to their feeding habits. Sucrase and maltase activities were found to be highest in the midgut of all species compared to other regions of the intestines. The lowest activity of γ-glutamyltranspeptidase (γ-GT) was found in the foregut of all species compared to other regions of the intestines. Alkaline phosphatase and γ-GT activities in the pyloric caeca of tilapia and bass were similar to those found in the intestines, indicating that these organs are an extension of the intestines where active protein degradation takes place. Copyright (C) 1999 Elsevier Science Inc.