[^^•^] POND CULTURE. .-,,S^ 



will fully repay by their increased growth any addition, if ever so sli.-i.t 

 to their natural food. This is fully proved by the results obtained in 

 ponds which have been sowed, or in ponds which receive much nutritive 

 matter with their water supply, or in which cattle occasionally deposit 

 their excrements, if compared with ponds where none of these condi- 

 tions exist. Under favorable circumstances, such as those mentioned, 

 it IS no rare ease that carp weighing ^ pound reach a marketable weight 

 in one summer. I can mention such cases from my own experience, and 

 from that of entirely trustworthy persons. Thus Delius mentions, from 

 his own observations, that he has known carp to grow from 132 grams 

 to l» i)Ounds (9G0 grams) in a single summer; and adds that he has' been 

 informed of still more astonishing resultsby reliable authorities. It may, 

 therefore, be recommended for all ponds which do not have a sufficient 

 quantity of food, or which are not in a natural way supplied with such 

 food, to add some artiticial food every day, or at certain stated periods; 

 and in any pond, where it can be done, artificial food should bo intro- 

 duced from September, the time when the natural food begins to de- 

 crease, and when the weather grows cooler, and when the feeding proc- 

 ess is to serve likewise for supplying that degree of heat which is nec- 

 essary for the growth of the fish. Heat, as is well known, is a most 

 important element in the growth offish, and the results both of natural 

 and artificial food should always be judged from the stand-i)oint of 

 an equal temperature. 



The experiences gathered from the Wittingau pond farm show that 

 the increase in the weight of carp was 10 per cent in May, 30 in June, 

 35 in July, 20 in August, and 5 in September. The greatest increase, 

 therefore, was in July and the smallest in September. We are, there- 

 fore, justified in supposing that in July nature supplies the normal 

 quantity of food needed by fish, leaving out of the calculation the ele- 

 ment of heat and the varying quality of the ponds. If we intend to keep 

 up the same supply of food during all summer, we would have to add in 

 May 25 ])er cent of artificial food, in June 5, in August 15, and in Sep- 

 tember 30 per cent. 



Even supposing that, owing to the great extent of the pond farnj, it 

 is impossible to introduce a regular system of feeding in all the ponds, 

 throughout the entire period of growth, for the simple reason that the 

 I necessary labor cannot be obtained, it should on no account be omitted 

 I m September; for, as we have seen, this month furnishes the least food 

 , for the fish, while this is the very time when, in stock ponds, the fish 

 I should be fattened for the market. Let us, as an example, see what 

 , will be the results if ground meat is fed to the fish from the beginning 

 I of September till the middle of October, /. c, forty-five days. We will 

 , suppose rhat a pond having an area of 10 hectares has been stocked 

 I with 1,200 carp, weighing each 1^ pounds, which by the end of August 

 I have reached a weight of 2 pounds apiece, whose entire original weight 

 ' has therefore increased from 1,250 to 2,100 pounds. The increase would 



