94 FISH CULTUEE 



three tiers, the fall must be nearly five feet. It 

 is now considered immaterial whether the 

 ponds are below or above the natural surface, 

 so long as the water can be successfully brought 

 into the first set of ponds and from thence in 

 a well aerated condition to those below. The 

 more quickly the water can be passed through 

 the better, provided a proper volume be not ex- 

 ceeded, particularly where fingerlings are being 

 held. 



Planning an E'stahlishment. — There must 

 be at least five ponds for the smallest establish- 

 ment; one for the advanced fry or fingerlings, 

 on their removal from the nursery troughs, a 

 second in which to place fingerlings after they 

 have been sorted in the summer; a third for 

 yearlings; a fourth for two-year-olds and a 

 fifth for three-year-olds and over, providing 

 such fish are to be retained. If the plant is to 

 be of any considerable size, the location and type 

 of the whole series of ponds ought to be well 

 considered and planned, even though there be 

 no intention of buildiag some of them for sev- 

 eral years. They should be as carefully con- 

 sidered and planned as a house. 



