566 EEPORT OF COMMISSIONER OF FISH AND FISHEPJES. [28] 



Carp are raised in ponds, where they are kept either by themselves 

 or in company with other fish. Different kinds of ponds are used in 

 carp culture, namely, spawning ponds, raising ponds, growing ponds, 

 and winter ponds. 



The water of the spawning ponds should be somewhat warm. This 

 condition is obtained by having these ponds exposed to the sun, by 

 changing the water slowly, and by selecting such as are not very deep, 

 the average depth of water not being more than one meter [3£ feet]. 

 Vegetation should be abundant, but not excessive. Eeeds and grasses 

 which soon cover a pond, should be checked in their growth. If pos- 

 sible, Mr. Haack would remove all the phragmites from the numerous 

 ponds at Hiiningen. Among aquatic plants the Glyceria fluitans is use- 

 ful, and much sought after by the carp, which deposits its eggs on it. 



To regulate the spawning of carp, Mr. Haack advises to place the 

 fish intended for that purpose in comparatively cold water, and thence 

 take them at the proper time to the spawning ponds, where, stimulated 

 by the higher temperature of the water, they will soon deposit their 

 eggs. Benecke, on the other hand, advises to place the carp in the 

 spawning ponds when their water still has the winter temperature. 



The number of spawning fish to be placed in a spawning pond cover- 

 ing an area of from one-tenth to half an acre should, according to 

 Max von dem Borne, not exceed two females and one male, each weigh- 

 ing 8 pounds, from which in a few days two to three thousand young 

 fish will be obtained. A single carp weighing 8 pounds is, therefore, 

 capable of producing enough young to stock 500 hectares [about 1,235 

 acres] of ponds. Mr. von dem Borne has had seventeen successive 

 spawnings in water having a temperature of 31° C. [about 88° Fahr.]. 

 It is therefore not at all surprising, if Mr. Haack states that he has real- 

 ized from the above-mentioned number of carp in one pond, which costs 

 hardly $10 to keep up, the sum of $300. 



Mr. Haack informed me that, in order to preserve all the good qual- 

 ities of the carp which he cultivates, he is very careful in selecting his 

 spawning fish from among those which from time to time are furnished 

 him for the purpose, selecting those which are not only sufficiently 

 robust, but which also possess all the other requisites of form and color 

 which make them desirable spawners. He therefore applies the true 

 principles of rational selection also to these animals. 



The artificial fecundation of the carp is possible, but it is very little 

 practiced. The fish-culturist is contented in most cases to leave to the 

 carp the care of laying its eggs. Some people inclose the spawning 

 fish in non-floating and perforated boxes containing branches and awl- 

 shaped leaves (juniper branches in Mr. Eckardt's establishment), which, 

 as soon as they are covered with eggs, are placed in more suitable 

 water. Professor Nitsche advises experiments with the artificial fecun- 

 dation of carp, using frames covered with some silk stuff, like those 

 used by Mobius for herring. Fecundation should of course be aceom- 



