540 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. [74] 



has not been ascertained in the beginning, a few years of experience will 

 be sufBcient to find tlie proper standard. If, however, the plan of man- 

 aging a pond farm does not appear to be absolutely erroneous during 

 the first year, one should be slow in introducing changes ; and if they 

 seem unavoidable, the outlines of the system once adopted should be 

 preserved as much as possible, so as to prevent injury to the entire 

 farm from a failure of such changes. If among the ponds there are 

 some which are not adapted to carp-culture, it should be considered 

 whether they could not be more profitably employed for raising or keep- 

 ing other fish, as trout, eels, &c. As the largest ponds should be used 

 for stock ponds, and as consequently one will have to deal with a given 

 area which possibly is still too large, if compared with the area remain- 

 ing for spawning and raising ponds, it will be necessary either to over- 

 stock these iionds and sui)ply the lack of area, and consequently of 

 natural food, by artificial feediug, or to buy fish for stocking the stock 

 pond to its full capacity, or prolong its course for another year ; in 

 which case, however, no fish of prey should be placed in it at least dur- 

 ing the first year, as the carp would have to enter it when ouly two 

 years old. 



In order to derive the full profit from a pond, i. c, to stock it in such 

 a manner as to cause it to } ield the best possible result, one should know 

 how many pounds of fish can be raised in it per annum, and from this it 

 can be calculated how many fish will have to be placed in a pond to raise 

 witiiin a given time a certain weight of fish. This should be known es- 

 pecially as regards the stock pond or ponds, for, being the largest 

 ponds, they should yield the largest income, and in proportion as this 

 object can be reached, oue should regulate the stocking of the spawning 

 ponds and raising ponds. From autumn till spring — generally from Oc- 

 tober till April — there is a pause in the growth of cultivated fish ; and 

 not till vegetation begins to revive do they again commence to grow. 

 Frequently half of the month of May is included in this period of rest, 

 as the weather is often cool enough to cause the fish to seek the deep 

 water. In September the weather again grows cooler, the number of 

 insects, worms, and plants on which fish live begins to diminish, and it 

 is therefore a rare case if carp, or any other cultivated fish, increase in 

 weight during the second half of September. Fish of prey, as a gen- 

 eral rule, grow more rapidly than tame (cultivated) fish, provided there 

 is a sulficient quantity of food; but they rest only for a short time dur- 

 ing winter, and pursue their warfare against other fish during the re- 

 maining portion of that season. Ilorak remarks relative to the growth 

 of carp : "During average years the increase in weight will generally 

 be as follows: in May, 10 per cent; in June, 30 per cent; in July, 35 

 per cent; in August, 20 per cent; in September, 5 per cent. Total, 

 100 per cent. 



"If the weather throughout the entire month of May ?s warm and calm 

 tlie increase in weight during that month maybe twice as great as that 



