592 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [54] 



which yields 10,000 cubic meters [about 350,000 cubic feet] of water per 

 day. Close to the hatching house it falls about 4 meters [13 feet], and 

 is partly gathered in an open wooden canal, which serves to bring it 

 into the hatching house. It is not filtered. Its temperature, even in 

 very cold winters, is 2° to 3° C. [35.6° to 37.4° F.]. 



There are in all seventy-two troughs, generally double, arranged in 

 three rows. Some of them are still of wood, but they will soon be re- 

 placed by others of cement. 



There are many ponds and basins for fish of different kinds, intended 

 for raising fish and for selling them. The principal object of this estab- 

 lishment is to raise young salmon for the Rhine, but it also hatches eggs 

 of common trout, lake trout, American trout, American Salvelinus, and 

 California salmon ; likewise crucians, carp, gold tench, and other cypri- 

 noids. 



IV.— Fish-Cultural Methods, 



There are two methods in use for increasing the number of different 

 kinds of fish : The first, in which human influence is reduced to its mini- 

 mum, consists in placing the fish under the most favorable conditions 

 for spawning. This may be called protective fish-culture, and is known 

 by the name of " pond-culture;" it is particularly adapted to the cypii- 

 noids, and among these specially to the carp. 



By the second method the eggs are taken from the fish, mixed with the 

 milt, and hatched, and the young fish are cared for and fed, until the 

 suitable time has arrived for placing them in the water; natural pro- 

 cesses are followed as closely as possible, and all hurtful influences kept 

 away. This last is genuine artificial fish-culture, and is especially ap- 

 plicable to fish which, like the salmonoids, spawn in winter, and conse- 

 quently do not develop too rapidly. 



Protective fish-culture does not demand so much care as artificial 

 fish-culture, and can easily be carried on even on a large scale. In fol- 

 lowing the protective method the fish-culturist should confine himself 

 to providing favorable conditions for the fish which he intends to raise, 

 leaving all the rest of the work to nature. If carp are to be raised, there 

 are placed (in the spawning-season) in a small pond, covering an area of 

 1,000 square' meters [10,704 square feet], which has been kept perfectly 

 dry until a few days beforehand, two male and one female fish, which 

 have been carefully selected. These fish will spawn in a few days, and 

 the young fry will develop very rapidly. After they have lost the um- 

 bilical sac they should be placed in a larger pond, covering an area of at 

 least 1 hectare [2£ acres], or in the waters for which they are intended. 

 The bottom of the pond used for reproducing carp and other cyprinoids 

 should be muddy; while for bass, American perch, and other fish it 

 should be gravelly. By allowing the carp to spawn on juniper branches 

 Mr. Eckardt has succeeded in conveying the eggs from one pond to-the 

 other, and he ships them by railroad in the same manner in which the 



