GROWING THE LARGE TROUT. 225 



emergency. Their food, when wild, consists chiefly 

 of water insects, smaller fish, larvse, fish eggs, Crusta- 

 cea, and the flies and insects which fall from the air 

 into the water, — all of them together forming an 

 astonishingly extensive variety. They also eat each 

 other, and there are some individuals which adopt 

 cannibal habits altogether, and remain hidden, like 

 spiders, in dark holes and corners, and only emerge 

 to devour their like. 



The quality of their food affects the growth and ap- 

 pearance of trout, and it is even thought that the dif- 

 ference in the color of their meat is sometimes caused 

 by certain kinds of feed ; the fresh-water gammari or 

 pulex being supposed especially favorable to the pro- 

 duction of red-meated trout. There are different theo- 

 ries about it, however. 



It is certainly true that their growth depends very 

 much upon the nature of their food. Francis, in his 

 Fish Culture, mentions the following experiment, of 

 which he says he once heard.* 



" Equal numbers of trout were confined for a certain 

 time by gratings to their several portions of the same 

 stream. The fish in one of the divisions were fed en- 

 tirely on flies, in another upon minnows, and in the 

 third upon worms. At the end of a certain period, 

 those which had been fed on flies were the heaviest 

 and in the best condition, those fed on minnows oc- 

 cupied the second place, while those fed on worms 

 were in much the worst order of the three." f 



* Francis on Fish Culture, p. 113. 



t The result of these experiments should be received cau- 



