[121] POND CULTURE. 537 



fish at stated periods, especially during the summer months, with a view 

 to ascertain the increase in weight during these periods. 



To find the natural capacity of the different ponds for producing food 

 according to the difference of soil and the more or less sunny location' 

 ponds of the same size should be constructed in different localities and 

 be stocked with an equal number of fish. The most favorable dimen- 

 sions of experiment ponds will be 10 meters in length and 10 in breadth, 

 with a depth of water as indicated in former chapters. 



These hints must suffice ; and the rest should be left to the ingenuity 

 and skill of the experimenter, which will enable him to find the sliortest 

 way to reach the desired end. Scientific education, a knowledge of the 

 principles of fish-culture, combined with the greatest exactness in mak- 

 ing experiments and observations, and the careful noting down of every 

 observation, are absolutely necessary to insure success. The experi- 

 menter must be able to distinguish the essential from the unessential, 

 and, fully alive to the great importance of his efforts, enter into the sub- 

 ject with enthusiasm. Only a person who is thus qualified will be able 

 to gather all the necessary data and therefrom draw his conclusions 

 with mathematical accuracy. A person who does not possess the neces- 

 sary education, or who shuns the labor and seeming waste of time con- 

 nected with such experiments, had better not attempt them. It will be 

 a great mistake to intrust the conducting of these experiments to serv- 

 ants or other uneducated persons, for even if you give them the fullest 

 and most accurate instructions, they will not carry them out fully, 

 either from a lack of intellect or because they do not take sufficient in- 

 terest in the subject. Even if they begin all right, they will soon get 

 nito a routine way of doing things and neglect one or the other of the 

 instructions. In short, these experiments should be conducted by no 

 one else but the educated proprietor or manager of the pond farm in 

 person. 



Supervisio7i of the jionfh.—Wehnve to mention the subject here as the 

 third point in the care of fish, but we deem it proper to reserve its full 

 discussion to a later chapter, and give first all those subjects to which 

 I this supervision relates. 



11. THE WINTERING OP FISH, OR THE STOCKING OF WINTER J>ONDS. 



j The object of winter ponds is to receive the older fish, and also in 

 I some cases the young fry, from ponds which, owing to their small 

 I size and insufficient depth, do not afford safe winter-quarters for fisli. 

 ! Besides the regular stock of fish, these ponds may also, according to 

 I circumstances, be used for those fish which are kept for sale, if there 

 I IS no chance to sell them immediately after the autumn fisheries, but if 

 j It IS likely that they can be sold during winter; as, confined within a 

 j narrow space, they can easily be caught whenever needed. If they were 

 left in the large stock ponds it would frequently be impossible to catch 

 them; and such winter fisheries will also invariably be conuectcd with 



