As sequel to Aquatic Animal Nutrition "“ A Mechanistic Perspective from Individuals to Generations, the present treatise on organic macro- and micronutrients continues the unique cross fertilization of aquatic ecology/ecophysiology and aquaculture. This treatise considers proteins and their constituents, carbohydrates from mono- to polysaccharides, fatty acids from free acids to fat, and waxes. It becomes obvious that these organic nutrients are more than only simple fuel for the metabolism of animals; rather, their constituents have messenger and controlling function for the actual consuming individual and even for succeeding generations. This aspect will become particularly clear by putting the organisms under consideration back into their ecosystem with their interrelationships and interdependencies. Furthermore, micronutrients, such as vitamins and nucleotides as well as exogenous enzymes, are in the focus of this volume with known and still-to-be-discovered controlling physiological and biomolecular functions.