83 



transport them quickly to the cold ponds devoted to 

 the rearing of Salmonidse, 



The fish culturist must proportion the number of 

 young of the Cyprinidse which he will need to the 

 number of Salmonidse which he desires to feed, and 

 experience will quickly teach him this proportion, 

 which will of course vary with the surrounding condi- 

 tions and the additional nourishment, more or less, 

 which can be obtained from the worms and insect 

 larvae in the pond ; besides, if there should be a surplus 

 of food for the Salmonidse he can easily sell it to other 

 fish culturists. 



As a general rule, the 3^oung carp and tench will 

 be eaten up before the}' have reached the length of 

 eight centimetres. No advantage is to be derived from 

 allowing them to grow larger. Every year the fish 

 culturist will then secure a new production of fr}^ 

 There is nothing in this which is either complicated or 

 calculated to embarrass the fish breeder. 



Let us proceed now to the arrangement of the cold 

 ponds (I repeat that by cold ponds I mean ponds in 

 which the water is not more than i6° centigrade). 

 Nevertheless, since we have to do here with California 

 salmon, we maj^ consider as cold ponds those in which 

 the temperature rises to 24° centigrade during the heat 

 of summer, that is to say, a truly cold pond of the ordi- 

 nary kind for Salmonidte is not a necessit}^ in this 

 method of culture, which has succeeded marvelousl}' in 

 regions provided almost entirely with warm ponds, as 

 at Sologne. 



Since a localit}' always contains some ponds which 

 are cooler than others, I recommend to the fish cul- 

 turist to give the cooler ones the preference in rearing 

 the California salmon. There are a number of reasons 

 for this which I will not enter into here. 



It will be well to arrange beside these ponds one or 

 two moderately large elongate basins, in which the 



