In intensive aquaculture, basic studies on fish digestive capacity and metabolism play a key role for diet formulation. In particular, intensive rearing of a new species is strictly related to the development of appropriate nutritional protocols and therefore knowledge of specific features concerning physiology and nutrition is needed. Nutrient utilization by fish is a direct function of the availability of suitable digestive enzymes along the gastro-intestinal tract. Therefore the determination of specific enzymatic activities (proteases, carbohydrases and lipases) may provide qualitative information about the digestive capacity and the efficiency of each reared species to use feeding components. Recent observations on digestive enzymatic profiles and on digestive ability of some Teleost species with large aquaculture potential and recognized as new candidates for product diversification have been reviewed in this paper. Attention has been given to the different features (dietary composition, digestive phases, life stages, contribution of bacterial .enzymes) that may affect enzymatic patterns.