No. 5 (I917) CARP-GROWING IN GERMANY 155 



remaining in the pond is insufficient for the growing survivors, and 

 they are therefore turned into larger and deeper ponds at the rate 

 of about 500 per acre, and thence again into larger ponds. The 

 system is desirable only where the waters are not incessantly and 

 largely under renewal, are not rich in natural food, and are not 

 supplied with artificial food ; otherwise the periodical transference 

 is unnecessary, since it is merely adopted to regulate the food 

 supply which enables the fish under this system to grow twice as 

 quickly as they do in ponds under the ordinary system, and to be 

 more healthy, since they are not starvelings crowded promiscuously 

 together, but well fed carplets with plenty of room and nutriment. 

 In Geeste where the waters are naturally very poor, this method is 

 essential ; the soil in which the ponds are dug is of the poorest, and 

 the ponds are merely filled occasionally with canal water and are 

 not continually changed by a continuous flow. 



The object of the construction is to reclaim hitherto useless 

 heath land by alternately growing carp and oats or other hardy 

 cereals or grass. The dry bed of a pond is manured in the usual 

 way and a crop taken ; it remains more or less dry (frozen) during 

 the winter, after which the water is let in and a crop of carp taken. 

 These subsist on the fish food in the water, which is rendered more 

 prolific by the balance of the unassimilated manure and the 

 leavings of the cereal crop ; the next crop of oats is benefited by the 

 excreta, etc., of the animal crop ; gradually the soil is enriched, 

 and with it the successive crops. 



The ponds are nicely arranged to avoid undue labour; the 

 breeding and nursery ponds are rectangular with proper sluice 

 arrangements and with central and cross ditches in which, when 

 the ponds are drained, the fry or fish collect and are therefore 

 easily netted, while the growing ponds are just large expanses of 

 water of irregular shape. The canal water is let in by a main 

 sluice, and to prevent predaceous fish from entering with it, the 

 water is strained by having to pass through a semi-circular wall of 

 road metal, which effectually filters it of anything so large as fish 

 fry. From April to November operations continue as above 

 described ; a little artificial food is occasionally given such as dry 

 fish powder from' Gesstemunde, etc., but this is not relied upon. 

 The resulting fry as seen in July were remarkably vigorous and 

 healthy and gave every promise of a successful crop ; they were 

 certainly much better than those of similar age seen two weeks 

 earlier in Bavaria. In November the ponds are drained and the 



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