[7] EAISING CARP AND OTHER POND FISH. 1139 



What magnificent carp, both as to size and flavor, are occasionally caught 

 in our streams! There can hardly be a doubt that they escaped, as 

 young fry, from some pond farm, or were allowed to escape, because their 

 number was too large. 



Much has been said in our days about mirror, leather, and blue carp. 

 They are generally thought to possess a more delicate flavor than carp 

 with scales, and if properly raised they will grow just as rapidly. 

 Dubisch justly considers it very important that only the best-formed 

 carp and those which have grown most rapidly should be used for raising 

 purposes. 



Construction of a pond.— Only in rare cases is a pond constructed 

 by digging a great pit in the ground. Generally it is done by erecting 

 a dike in the lowest place of some low ground. A pond may often be 

 constructed at very slight expense by closing up the ditch which in 

 former times has served to drain swamps or lakes. According to the 

 different manner in which ponds are supplied with water, we distin- 

 guish : 



Brook and river ponds, which are fed by running water ; 



Spring ponds, which are fed by springs ; and 



Sky ponds, which are fed by the rain and snow wa.ter or from ditches 

 which dry up in hot weather. 



The dike is made from the nearest material at hand, and at the same 

 time the fish-pit is constructed. The best material is loam and clay. 

 In sandy soil the dike and the pond should have a foundation of loam 

 and clay, unless the supply of water is ample at all times, as otherwise 

 there is danger that the water of the pond will gradually leak through 

 the ground. 



To drain the pond a pipe is laid right through the dike, which can be 

 closed and opened on the water side. This pipe may be either of wood 

 or of burnt clay or of brick's laid in cement. In sandy bottom the pipe 

 must be tight, as otherwise the sand will enter and be 'carried away 

 with the water, so that the dike begins to sink and the water of the 

 pond flows out. In sandy bottom, wooden pipes should therefore al- 

 ways be set in cement. The tap-house is located at the end of the pipe 

 on the water side. It consists of a wooden grate, which prevents the 

 fish from entering the pipe, and of a safety-valve for letting off the 

 water. Iron grates are not suitable, as they are soon destroyed by 

 rust. 



The fish-pit is a deep place near the tap -house, in which the fish con- 

 gregate when the water is let off. It should be so constructed that it 

 can be laid entirely dry, be large enough, and have a firm bottom. If 

 the soil is loose, its bottom should therefore be strengthened by sand, 

 gravel, and stones. 



The outer pit is a deep place where the water goes after it has left 

 the pipe. It is destined to receive the fish in case the grate has been 

 damaged ; and at the place where the water flows out of it there should 



