TROUT FLY-FISHING IN AMERICA 



Coloration of Trout 



The coloration of trout is due to a number of separate 

 and distinct factors and elements, each one of which per- 

 forms some special function. These factors are naturally 

 divided into two classes — internal and external. 



Those which influence coloration from within the fish 

 are called internal and those which influence coloration 

 from without are called external. 



Internal Factors: 



Internal Elements: 

 External Factors: 



External Elements: 



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Position of the pigment cells. 

 Activity of the pigment cells. 

 Kind or character of food. 



The breeding season. 

 The age of trout. 



Character of the water bottom. 

 Kind or degree of light. 



Kind of day. 

 Condition of the water. 

 Season of the year. 



The coloration of trout is made possible by the pres- 

 ence of innumerable pigment cells which are located at 

 different depths of the skin and on or near the surface of 

 the scales. 



These cells, due to their nature and position, are ren- 

 dered extremely sensitive and therefore are susceptible to 

 rapid changes which make effective the different pigment 

 colors. 



The changes in coloration are caused by conditions 

 which influence the activity of the pigment cells, thus in- 

 creasing or decreasing the accumulation of the numerous 



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