81 



should be to insure abundant nourislinient for the fish. 

 In the culture of the carp, which is herbivorous, the 

 ponds must be well supplied with certain species of 

 aquatic plants. I have insisted so strongl}^ upon this 

 point in my recommendations for the last ten years 

 that man}^ proprietors of ponds begin to recognize its 

 value. 



At present we seek to raise carnivorous fishes, and 

 all our efforts should lead primarily towards securing 

 an abundant supply of animal food. Certain special- 

 ists have believed that they could solve this problem 

 by an unlimited supply of crustaceans ; this is the S3'S- 

 tem of Lugrin. I have demonstrated in experiments 

 made at the Trocadero Aquarium that feeding by 

 means of daphnia is simply a dangerous illusion. These 

 little animals possess very small value as food, and 

 fish which are subjected to this regime do not grow. 

 But it is important to the fish culturist that his prod- 

 ucts grow as quickly as possible, and to accomplish 

 this we must not forsake food materials of rich quality, 

 like meat, blood, etc. 



We employ the two series of ponds, of warm water 

 and cold water, for different purposes. The warm 

 ponds in which fish reproduce and grow rapidl}"-, because 

 plants grow in them, are used to raise herbivorous fish 

 of rapid growth, like the carp, tench, and roach. 



In this new method of culture the carp and its 

 rearing does not entirely disappear. It is simply rele- 

 gated to the second place, and cultivated, not for the 

 purpose of obtaining fish of marketable size, but for the 

 fry, which are intended for feeding the Salmonidse. 

 Carp, roach, and tench, hardy fishes of which the 

 multiplication is unlimited and the growth rapid, will 

 be grown in warm ponds, but produced in such a man- 

 ner as to remain small, and in order to obtain this 

 result we allow the breeding ponds to be overstocked 

 with eggs, a thing which was avoided carefully under 



