(2) The nursery ponds, tihile still oon^)letely dry shoiild be sown with weeds and 

 grasses since this will greatly improve bottom conditions. After the filling 

 of tlie pond, but before stocking them, paths are cut through the weeds and the 

 mowed-off plants are set up in stacks. Later on, when the brood has reached 



a length of 3 centimeters, these stacks are again distributed in the pond. 

 The oxygen content of the water — on account of the rotting process of the weeds — 

 has to be constantly watched. The ponds are also to be treated with mineral 

 and organic fertilizer but again in such a manner as to avoid lack in oxygen. 

 Strong and frequent doses of liquid dung, of blood meal and of fish meal and 

 general care are also necessary. As a result, water fleas (Daphnia pulex) will 

 develop plentifully and will protect the brood from want of food even during 

 the months of June and July when the larvae of Chironomida begin to slip their 

 eggs. 



(3) After drainage, the ponds must be properly disinfected with quicklime. 



(i4) As soon as lack of food becomes noticeable and the brood does not grow well 

 enough, the fish are to be removed from the nursery ponds and transferred 

 into the rearing ponds. 



(5) The amount of stock for each pond must be carefully regulated. In average, one 

 figures about 50,000 broodfish per hectar (2 1/2 acres), but this is to be so 

 regulated that the brood attains an average length of from 5 to 6 centimeters 

 during the first four weeks. By utmost care as much as 200,000 brood fish can 

 be stored per ha. To merely let the brood slip from the spawning ponds into 

 the nursery ponds is strongly counter-indicated, since this will inevitably lead 

 to slip^shod methods. 



With regard to the injurious effects of nursery ponds, formerly and still lately 

 held by many (Schaeperdaus, 1930) only onfe objection deserves real notice. 



It was said that on account of the necessary fishing-out of the brood in June — the 

 most dangerous time for Dactylogyrus affection — the slightest weakening of the brood 

 would expose them to this dreaded disease. 



This is easily remedied — ^where Dactylogyrus occurs notwithstanding the best of 

 care — by rearranging the management of the ponds, i.e. postpone the fishing-out until 

 the end of July or even the beginning of August, This also means that the nursery ponds 

 are stocked somewhat less with brood, in order to provide sufficient food for the pro- 

 longed period of stay. Seme fishbreeders, on the other hand, obviate the danger of 

 Dactylogyrus affection by advancing the fishing-out time. 



But whatever method of "nursing" is employed, the nursery ponds will produc<3 — be- 

 tween June and the beginning of August — relative large broodlings of about 2 to 9 centi- 

 meters in length. (At an early date of fishing-out, they will be about 2 to 3 centimeters 

 long, while by fishing them out at a late date they will have reached 7 to 8 centimeters.) 

 In this latter case, it is advisable to use sorting tables which permit the 

 separation of the brood according to size and development of scales (developed already 

 when the fish are only 1.8 centimeters long). By using these tables, one can also 

 separate the broodlings from tadpoles, tench eind other fish, 



(c) The raising of yearlinRS, 



TIThen raising yearlings, the young carp are transferred from nursery ponds into 

 rearing ponds which can be of most any size. It will facilitate the fishing-out, though, 

 if these ponds are not all too large. 



These rearing ponds should have a depth of at least 1 meter in order to avoid — in 

 case of prolonged storing — an over-growing with weeds (see Pig, 20), It is still better 

 to give these ponds a depth of from 1,50 to 2.00 meters, i.e., near the outlet (raynk). 

 In this case the yearlings can hibernate in these rearing ponds. It is to be remembered 

 that the broodlings are very sensitive to fishing-out in the fall and are especially in 

 need of food during the winter. The Dubisch procedure surpasses all others by sparing 



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