About 2 to 3 days after spawning — and at a water temperature of 15 centigrades — the 

 embryos become visible in all live eggs. The nonfertilized and dead eggs are by now milky 

 white. The alevins emerge from the eggs within about 6 days, according to Stankowitch, 

 i. e. at a vrater temperature of 15 degrees centigrade In warmer waters this process 

 occurs naturally somewhat faster, while in cooler waters the process is somewhat slower. 

 The alevins are about 5.5 millimeters long. In the beginning, the alevins hang to the 

 grass stems but soon begin to swim about. In comparison with the vitelline sac of trout 

 brood, the vitelline sac of carp alevins is rather small, i.e. contains less nutriments. 

 The consequence is that this food is consumed within 8 days — the alevins are now about 

 8 to 10 mm. long — and the brood begins the active need for and taking up of food, even 

 before the nutriments of the vitelline sac are completely consumed. 



In the small iDubisch ponds this cannot be done for any length of time, therefore 

 the alevins are brought into larger and more nutritional ponds — latest within a week — 

 the so-called nursery ponds. The alevins are now about 9 mm. long. 



(b ) The rearing of brood in nursery ponds . 



The nursery ponds for accommodating carp brood by the end of May or in June are still 

 relatively small since this in itself assures the possibility of proper care and also 

 facilitates the future fishing out. Both factors must absolutely be taken into consider- 

 ation. Too small ponds — on the other hand — have their disadvantages. It is best to 

 adjust the size of nursery ponds to the planned sojourn of the brood in them. 



If only a short stay is contemplated — of about U weeks — the size of a nursery pond 

 should be lYom about 0.25 by 1.00 hectar (1/2 to 2 1/2 acres). If an eight weeks stay 

 is planned, larger ponds of even 3 hectars area (7 l/2 acres) are of great advantage. 

 The average depth should be about 50 centimeters. Too shallow ponds are exposed to 

 strong changes in temperature, while deeper vrater will naturally take longer to warm iQ>. 



Fig. 18. Living carp brood (Alevins) shortly after hatching 

 (Taken from the UFA-Culture Film "Secrets of the Egg Shell" 

 with the collaboration of the author.) 



83 



