ABSTRACT
Air and water are dramatically different media. The greater viscosity of water is used to advantage by many aquatic organisms as an aid for locomotion. Most aquaculture species are poikilothermic, meaning that their body temperatures conform to the temperatures of their environments. The chapter discusses the major physical and chemical water quality factors that impact aquaculture. The quantity and quality of water are the most important considerations in developing an aquacultural endeavor. Some properties of water are of particular importance for aquaculture: the solubility of gases such as oxygen satisfies the respiration needs of aquatic organisms, and the high density enables organisms to remain in suspension and to move with minimal expenditure of energy. Lakes and seas receive nitrogen and phosphorus compounds from runoff and river inputs carrying wastes from agricultural, industrial, and other human activities. The aquatic organisms avoid the complex transformations and concentration of nitrogenous wastes that terrestrial animals must perform.
