[123] POND CULTURE. ~^<i^C) 



Winter ponds should be allowed to lie dry during summer, so that 

 the soil may lose its acidity, and also to prevent the growth of aquatic 

 plants. It will also be well to plow the winter ponds as soon as they 

 have been drained, and so let them remain in that condition for some 

 tiuie; or, better still, to sow them. A short time before the fish are 

 ]>laced in the winter pond it should be filled with water, so as to have 

 its full supply when the fish enter it. 



The number of fish to be placed in winter ponds will depend on their 

 size and quantity of water, on the depth of water and the depth to 

 which it will freeze in winter, on their supply of water, and on the size 

 and weight of the fish. Yon Keider counts, according to the size and 

 depth of a pond and its possible supply of water, 28,000 to 35,000 two 

 years' fish per hectare, but as a general rule only 17,500 per hectare; of 

 one year's fish, 42,000 per hectare; and of young fry, 84,000 to 105,000; 

 and large carp only 3,500 per hectare.* Horak (without specifying what 

 classes of fish he has reference to) counts in round figures 5,200 to 0,200 

 per hectare.t 



Every possible precaution should be taken to prevent any transfer of 

 fish from one winter pond to another, for if the water is low and its sup- 

 ply scanty this may seriously injure the fish, which are crow-ded in a 

 narrow space. 



Breaking holes in the ice and admitting air will not protect the fish 

 from dangers in the winter ponds ; but the only efficient means of pro- 

 tecting them is to give them sufficient room and a constant supply of 

 fresh water, which will not only provide the fish with air, but also pre- 

 vent the spoiling of the water, even if the surface is frozen firmly and 

 covered with a thick layer of snow. The case is, of course, different 

 in sky ponds, which during winter receive hardly any supply of fresh 

 water, and here it will be a matter of necessity always to have some 

 holes in the ice. 



In order not to make the sorting of the fish difficult when the winter 

 ponds are fished in spring and to make this process unnecessarily slow, 

 large and well-regulated pond farms should have separate winter ponds 

 for the different classes of fish, i. e., one for the young fry if it cannot 

 be wintered in the spawning ponds, one for the two years' fish, and one 

 for the three years' fish (if, after the fisheries, they are not immediately 

 transferred to the stock ponds). If other kinds of fish, especially fish 

 of prey, are to be wintered, they should be assigned separate winter 

 ponds, as they must on no condition share a pond with carp. Wher- 

 ever it can be done, those fish of prey which have not yet reached a 

 marketable weight, and can therefore not be sold, should immediately 

 after the fisheries be returned to the stock pond. This applies to ])ike, 

 perch, &c. If fish of prey are wintered, their winter ponds should be 

 separate from those of the other fish. Tench also should, if possible, 



* Von Eeider, Das Ganze der Fischerei, 1825. 

 t Horak, Ttichirirlhschaft, 1869. 



