Lydell. — Progress in Practical Fish Culture 223 



that has an abundance, letting it dry, and then scattering 

 a goodly supply over the bottom of the ponds that lack 

 vegetation. The reason for the introduction of goldfish 

 and crayfish is that they do not prey to any extent upon 

 the insect life that furnishes food for other kinds of young 

 fish. As the goldfish breed about a month later than the 

 other varieties of pond fish, their young furnish an abun- 

 dance of food later on. A pond vvrith plenty of shallow 

 margin will yield a greater number of fingerling fish; 

 this is because more food is produced in the shoal mar- 

 gin areas. 



INTRODUCTION OF BREEDING FISH 



The breeding fish are carefully sorted, both with, re- 

 spect to their size and condition, and none but strong, 

 healthy specimens of about the same size are placed in 

 each breeding pond. The number put in each depends a 

 great deal on its water area and the amount of natural 

 food available for their young. Before the fish are trans- 

 ferred from the storage to the breeding ponds, the tem- 

 perature is taken, and it is determined with absolute 

 certainty that the temperature of the water meets the 

 requirements of natural spawning conditions. If the 

 hatchery water supply is from a spring brook, it is shut 

 off from the breeding ponds, and the temperature of the 

 latter allowed to rise to a point where breeding will take 

 place quickly after the brood fish have been introduced. 

 The breeding stock is held in one or two of the deeper 

 ponds with an abundant supply of running water, and thus 

 spawning may be retarded several days. The fish are con- 

 stantly kept under close observation to see that breeding 

 does not proceed too far before they are transferred to 

 the warmer breeding ponds. It is far better to lose a 

 few eggs in the retaining ponds than to lose them all 

 in the breeding ponds, which latter will occur if the fish 

 are sorted too early. After the fish have been sorted and 



