In clear headwater streams, trout can reach impressive sizes at times. This is often because the water is very pristine and not influenced by the developments of man. Clear, unpolluted water often supports a large variety of insect life, including an array of various Mayfly, Stonefly, and Caddis Fly. It is these insects that rely on unpolluted water in which to live, and, when you find a stream of such quality, the fish can be in fantastic condition. Not only are the fish living with an abundance of food, but the water clarity also allows the fish to be able to intercept large food items at a distance, and thus feed more effectively. Below are examples of fish from such pristine rivers.