BULLETIN OF THE UNITED STATES FISH COMMISSION. 473 



129 TROUT A>D TROUT CULTURE." 



By K. A. KOSS. 



The brook trout belongs to a family of fish the members of which are 

 distinguished for their delicate flavor, and among which the salmon, 

 the king of all food-fish, occupies the most prominent place. The trout 

 is one of our most valuable fresh-water fish, and recommends itself to 

 the pisciculturist by many excellent qualities. The clearer, colder, and 

 more rapid in their flow the waters are in which the trout lives the 

 darker is its peculiar many- colored skin. It seems as if nature took 

 special care not to make its appearance too striking so as to attract the 

 attention of its enemies, of whom man, after all, is not the worst. The 

 trout, which in brooks reaches a weight of about three pounds, seldom 

 more, is a very hardy fish and not very choice in its food. It is not 

 timid, and can even be easily tamed, in which case, on account of its 

 voracity, it can be accustomed to take its food from a man's hand. It 

 is particularly well adapted to pisciculture, because its eggs are very 

 hardy and can easily be transported a considerable distance. Its power 

 of digestion is very extraordinary, and when well fed it grows quicker 

 than most other fish. Its food is exclusively animal, consisting princi- 

 pally of insects, larva 1 , snails, and other small animals. All these 

 water animals need aquatic plants for their existence, and these plants 

 are, therefore, necessary indirectly to the trout. It occasionally eats 

 fish, but never shows as much liking for them as for the other articles 

 of food mentioned above. When a number of trout living together 

 have sufficient food there will be among them but very few which eat 

 fish, perhaps only one in a hundred, provided that the difference of 

 size is not too great. The trout which eat fish grow quicker than their 

 comrades ; in retired places they lead the life of hermits, and their flesh 

 is less delicate than that of other trout. If one succeeds in catching 

 these destructive individuals no more fish will be eaten, for in the 

 shallow brooks there will rarely be any other fish of prey. Trout do 

 not like the company of other fish ; it is well, therefore, to keep them 

 separate from other fish as much as possible. 



For spawniug places the trout prefers shallow spots with a gravelly 

 bottom, over which the water flows slowly and with broken force; the 

 fecundity of the trout in a certain body of water depends altogether 

 upon the extent of suitable, spawning places. Whenever a brook has 

 large stretches of gravelly bottom over which the water flows gently, 

 it may be assumed with a great deal of probability that it contains 

 trout. For supplying trout with food it is well if there are occasionally 

 places where the bottom is muddy or peaty ; a slow current is also much 

 to be preferred to a rapid current flowing over a rocky bottom, because 



* "Forellen und ForeUenzucht." — Translated from tbe German by Hermann Jacob-son. 



