40 The Life Story of the Fish 



definitely established that protective coloration exists, and 

 that protective coloration does protect. 



Not all fishes have this ability to adapt their coloring. In 

 the tuna and the swordfish it is, so far as we can tell, very 

 little developed. These are fishes which spend most of their 

 time in the upper waters of the open sea. Here conditions 

 change very little, and there is therefore little need for color 

 change. The basic scheme of dark back and light belly is the 

 suitable dress for all occasions. 



The trouts live in a different kind of world. Sometimes 

 they are on a dark bottom, sometimes on light. Sometimes 

 they are in the sunshine, sometimes in the shadow. In color 

 and pattern adaptation they are far behind the flounder, but 

 their shade they can alter to meet conditions. With them, 

 too, the eye is the principal instrument in bringing the ad- 

 justment about, and this fact I learned before I ever looked 

 into a microscope. It was when I first fished the Test in 

 England many years ago. Catching trout in the Test is a 

 different problem from catching them in our American 

 streams. In the Test, the fish lie in plain sight, and the ability 

 to cast a dry fly with sufficient skill to make them want it is 

 the principal requirement. In our American streams, such 

 as the Broadhead or the Gunnison, to take widely separated 

 examples, the fish are almost never visible, and the knowl- 

 edge of where to fish for them is the first requirement. The 

 most skillful caster gets nothing more than an occasional 

 chance rise unless he knows where to cast. 



The Test is an exciting stream because there are always 

 lots of fish to be seen. One- and two- and three-pounders 

 float in the slow, clear water, fins just moving to hold them 

 against the current, sometimes as many as seven or eight all 

 in sight at once. You may see a thousand fish in the course of 

 a day, and yet, if you are no more expert than I was, have 

 difficulty getting as many as six. For only about one in six 



