To formulate balanced feed for aquatic organisms, it is necessary not only to know the proximal analysis, or the biochemical composition of the ingredients, but also the digestion potential, using enzyme extracts from the digestive tract (in vitro digestibility), its absorption capacity (apparent digestibility), its assimilation capacity (using direct methods, such as stable isotope of C and N) and evaluation methods of energy distribution. In this conference, different results obtained by the Aquaculture Nutrition Program of the UMDI Sisal, of the Faculty of Sciences of the UNAM, will be presented.