1122 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [22] 



other. If the size of a pond, the number and weight of the carp placed 

 in it, and the number and weight of the carp caught in it are known, it 

 will be easy to ascertain the yield of the pond per hectare. 



Short distances, from one pond to the other, the carp can be trans- 

 ported in baskets or portable nets, and also in wagons, packed in moist 

 straw. In this way they can be transported several hours. For greater 

 distances they have to be put in barrels, having a capacity of 1 to 5 hec- 

 toliters. These barrels should be watered for a long time before being- 

 used ; they must be quite smooth on the inside, and when intended to 

 receive fish, be filled two-thirds with water. For journeys occupying 

 several days, the fish have to be prepared, by keeping them in running 

 water for several days, and not giving them any food, in order that they 

 do not pollute the water in the barrels with their excrements. It is best 

 not to put more than 150 to 200 pounds of fish in a barrel holding 5 hec- 

 toliters. The water should be partly renewed several times a day, and 

 its temperature should not exceed 10° C. ; if necessar^^, it should be 

 cooled with ice. It is strongly to be recommended to introduce air di- 

 rect by means of bellows to which a. long rubber tube is attached. The 

 bellows can be worked by hand, or by the turning of the wagon-wheels. 



7. The cleaning and planting of the ponds. 



As has been stated above, it is advisable to let the ponds lie dry dur- 

 ing winter, in order to destroj?^ the vermin. In most ponds mud will^ 

 gradually accumulate, partly brought from the surrounding heights by , 

 the rainwater, and partly formed by decaying vegetable matter. On . 

 the edges of the pond mud becomes valuable, because it offers food for 

 numerous small animals, but in the depths it becomes hurtful, because 

 it is stirred by the violent motions of the fish and makes the water tur- 

 bid. When the ponds are laid dry it should therefore be carted away 

 once a year, or at longer intervals ; and when piled up in heaps it has 

 been allowed to drj-, it can generally be used as a fertilizer for meadows 

 and fields. 



By the planting of ponds we understand their use for cultivating 

 grass, clover, oats, &c., for a period of one to two years after they have 

 served the purpose of fish-culture for three to six years. The advan- 

 tages of this system of rotation have been known for centuries, and 

 consist in this, that by plowing, and by roots of plants entering the bot- 

 tom of the pond, it is loosened, and from the roots and stubble receives 

 many substances, which are dissolved in the water, and serve as food 

 for fish directly or indirectly. The mud which has accumulated in the ^ 

 pond during the period of fish-culture is moreover extremely fertile, 

 and will need no manure in order to produce a rich crop. The ponds are 

 generally sowed with timothy grass, clover, or oats, which yield a rich 

 harvest. In some places it is customary to plant the ponds with turnips, 

 ,,and to fl*l the pond with w^at^r in autumn, without taking them out. 



