[23 J UTILIZING WATER BY FISH-CULTURE. 1123 



Especially in ponds which are not traversed by a brook or river this 

 is a dangerous practice, as the water can easily be polluted thereby ; 

 under all circumstances such a pond should not be stocked till the fol- 

 lowing spring. 



8. The feedingt of carp. 



The growth of fish depends on the quantity of food to a much higher 

 degree than that of our domestic animals. In order, therefore, to ob- 

 tain satisfactory results in fish-culture, it is of the utmost importance 

 to give the fish an ample quantity of food. In the first place the ponds 

 should not be overstocked, and should be made to produce more fish- 

 food, by planting them from time to time. Many attempts have been 

 made to artificially increase the small animals which serve as fish-food. 

 Infusoria, diminutive crustaceans, and larvas of different insects will de- 

 velop in greater quantities in shallow, calm, and warm water than in 

 deep water; and it is therefore an advantage if the edges of the ponds 

 are shallow. Occasionally small pits are dug near the banks, and con- 

 nected with the pond by a narrow ditch. In these pits it is sought to 

 produce the conditions which attract insects about to deposit their eggs, 

 and which favor the development of these insects. Strongly diluted 

 manure water is a favorite place for gnats to deposit their eggs, and 

 the pits will soon swarm with larvae, large numbers of which will reach 

 ihe pond by means of the narrow ditch. If this process can be aided 

 by letting a small stream of water flow through the pit into the pond, 

 it is all the better. For filling these pits Stenzel recommends the leaves 

 of the alder, poplar, and beech. It is very desirable that systematic 

 experiments should be made relative to this manner of increasing insects, 

 &c., which form an excellent fish-food, especially for young fish. The 

 spawn of frogs forms an excellent food for fish, as also young tadpoles. 

 It may also be recommended to place above the surface of the water a 

 number of boxes with wire bottom, containing moderately sized pieces of 

 meat, which are soon covered with the larvsB of the blow-fly. As soon as 

 these larvae have became large and heavy, they fall into the water in 

 great numbers and form a welcome food for the fish. 



From times immemorial, attempts have been made to fatten carp by 

 giving them artificial food, and a number of vegetable and animal sub- 

 stances are suitable for this purpose. Only such substances, however, 

 should be employed which can be obtained cheaply, and which bear in 

 themselves the guarantee that the capital invested will bear rich in- 

 terest. Systematic experiments as to the comparative nutritiousness of 

 he different substances mentioned in this connection have not yet been 

 made anywhere, although they would be of great value to carp-cultur- 

 ists. Scientific institutions are generally not prepared to make such 

 experiments, as but very few of them have any ponds at their disposal ; 

 and fish-culturists who of late years have often sought advice from nat- 



