FOOD OF FISH AND ITS PRODUCTION. 105 



small, it should if possible be encouraged. Some 

 people are very fond of introducing minnows into 

 their rivers and lakes, to form food for the trout ; but 

 minnows, unfortunately, feed on precisely the same 

 kinds of food as trout. They are incessant rangers 

 in search of food, and very voracious, and before he 

 becomes food in his turn, probably a minnow of fair 

 size will, at a very low calculation, have devoured 

 twenty times his own weight of food ; and, conse- 

 quently, instead of benefitting the trout, the minnow 

 has deprived him of nineteen times its own weight of 

 varied food. This quite accounts for the fact of trout 

 often rather falling off and deteriorating in lakes into 

 which minnows have been largely introduced. Vege- 

 table-feeding creatures are rather what are required 

 than such as feed on other insects. 



