الفصل الثاني

The aquatic environment can be defined as an interacting system of resources such as water and biota. The world has a variety of lotic and lentic aquatic environments, which are a major source of food for millions of people across the earth. The abundance and distribution of fishes in the water are the products of interaction among fishes and their chemical, physical and biological surroundings. Hence, the dynamics of the aquatic environment depend on the properties of water. Environmental forces such as temperature, light, dissolved oxygen, current, and population density that impinge on the lives of aquatic animals are complex and interrelated in their effects.