ABSTRACT
This chapter discusses fish nutrition which is a specialized subject. Whether the fish are fed naturally or artificially their nutritional requirements are the same: they need proteins, lipids, sometimes carbohydrates, minerals, vitamins and growth-promoting factors, which may come either from the surrounding aquatic environment or from prepared diets. The nutritional requirements of fish do not vary greatly from one species to another. There are exceptions, for example, in the requirements for essential fatty acids and the capacity to assimilate sugars. In order to appreciate the effectiveness of a particular food, nutritionists have developed the concept of energy: energy can be defined as the capacity to carry out work. It is required for the muscular activity involved in movement, and also for all the metabolic processes carried out by the organism. Lipids are a better source of energy for fish than proteins. The chapter shows the relationship between crude and digestible energy for proteins, lipids and carbohydrates.
