THE HISTORY OF FISH-CULTURE. 503 



Coregonus, Ciiv. The young lavarets first feed on insects ; but, arrived 

 at a certain age, they also eat the spawn and young of the roach and the 

 ablet. Young trout and young salmon reguire running water where 

 insects cannot live, while the young of the lavaret requires more 

 stagnant water, because the insects which form his food can there 

 live and multiply. The spawn of the ablet and other small fish which 

 form the food of the trout, the salmon, and the lavaret is obtained in 

 every establishment of pisciculture by meaus of artificial spawning. As 

 the young fish during the first time of their existence, if the}^ were 

 placed in ponds and reservoirs to increase, would every minute meet 

 with innumerable and unavoidable dangers, (fish, insects, &c.,) and 

 "would perish uselessly, one ought, before transferring the young fish to 

 natural reservoirs, to raise them in fish-ponds, which are true nui-series.of 

 fish. According to the extent of the pisciculturist's business, these fish- 

 ponds may be merely boxes or ponds, or, in short, any reservoir where 

 the fish can be placed under conditions that are favorable to its develop- 

 ment, and where it can be protected against its various enemies while 

 it is still too feeble to defend itself. 



7. — TRANSPORTATION OF SPAWN. 



The most common way of transporting spawn longer or shorter dis- 

 tances is the following: A wooden pail is used, the bottom and sides of 

 which are covered with a damp cloth, which separates the layers of eggs ; 

 this cloth is always kept damp, and in its stead moss or certain aquatic 

 plants may be used, between which the spawn is spread. In doing this, 

 care should be taken that the eggs do not press against each other, and 

 that the pressure of the upper layers does not injure the lower ones. 

 The establishment of Nikolsky sends fecundated spawn in this manner 

 through the whole of Russia. The glutinous spawn Is transported with 

 the plants to which it adheres in glass bottles, filled to three-fourths of 

 their capacity with water, or in baskets and boxes wrapped up in damp 

 cloths. The vessels in which fecundated spawn is transported, especially 

 long distances, must always be wrapped in substances which are as little 

 as possible conductors of heat ; moss, felt, etc. For the different kinds 

 of salmon the temperature must be 32° to 50° Fahr., while for other fish 

 it must be higher. 



Whatever means of transportation be employed, spawn must not be 

 shipped immediately after fecundation, as experience has shown that 

 the best time for this is when the embryo has reached that stage of its 

 development when two black dots can be observed in the place of the 

 eyes. 



The transportation of fish depends on its age; the younger it is the 

 easier it can be shipped. Young fish scarcely hatched are sent in glass 

 vessels, the water on which must be changed every two or three hours. 

 This frequent change of water may, however, be avoided by passing a 



