[17 J UTILIZING WATER BY FISH-CULTURE. 1117 



reached a weight of 1| to 1^ pounds. Dubisch counts 206 of his two 

 summers' carp, weighing 1 to IJ pounds per hectare, and in autumn 

 catches 200 fish weighing about 2 pounds. If only 154 carp per hectare 

 are placed in the pond there should be in autumn 150 carp weighing as 

 much as 4 pounds. It will not hurt to keep in these ponds, besides 

 carp, some tench and eels, which root more in the ground than the carp, 

 and there seek food which would be no good to the carp. . 



As with spawning-ponds and "raising-ponds for fry," it is also best 

 if the raising-ponds are fished clear in autumn, and are allowed to lie 

 dry during winter. Only in exceptional cases, and taking the proper 

 precautionary measures, such ponds should be allowed to remain filled 

 during winter. 



3. Ponds for older fish (aRowiNG-poNDs). 



These ponds are intended for three-summers' carp, and here, accord- 

 ing to the quantity of food contained in them, they will in one to two 

 years reach a weight of 2 to 2^ pounds. In Ifubisch's method the rais- 

 ing-pond for two-summers' carp takes the place of the pond for older 

 fish, no other jDond being required, as it will be found most advanta- 

 geous to sell the fish when they weigh from 2 to 2^ pounds, because at a 

 more advanced age they use the same quantity of food as younger fish, 

 but produces less flesh. As ponds for older fish, large and deep sheets 

 of water may be used, which, according to circumstances, are only fished 

 • every two years. As deep and cool waters produce less food for carp 

 than shallow ponds, the ponds for older fish, especially if they are only 

 to be fished every two years, should not receive as many fish as the raising- 

 ponds, 150 to 250 per hectare generally being counted sufficient. It will 

 not hurt to put a considerable number of tench and eels in these ponds. 

 It is also advisable to place in these ponds a number of small fish-of- 

 prey. Especially in ]3onds which are connected with other waters, there 

 are generally found large quantities of fry of the bleak, the red bream, 

 and other fish of this kind. Even into ponds which have no connection 

 with other waters the spawn of such fish is frequently brought by wild 

 ducks and other aquatic birds which often carry large quantities of it 

 on their wings. These worthless fish, which only take away the food 

 from the carp, ought to be destroyed by perch and pike, and thus be 

 transformed into valuable fish flesh. It also frequently happens that 

 in hot seasons the carp spawn already in the ponds for older fish, when 

 of course the fry, being in cool water, and in the company of larger fish, 

 do not develop well. Even such useless fry is to be transformed into 

 valuable fish flesh by being devoured by fish-of-prey. This is the advan- 

 tage of having " a pike in the carp pond," that' it frees the carp from use- 

 less competitors for its food, whilst it grows quickly, and its flesh be- 

 comes particularly tender and well flavored. The old fables that the 

 pike chases the lazy carp and forces them to take food, and that it pre- 



