12 FISH PONDS ON FARMS. 
there are adjacent waters to which the fish can be removed during 
this process. A number of small auxiliary ponds will always be 
found advantageous in fish-cultural work. 
Where the primary purpose is other than fish culture the selection 
of the site must depend upon the more important object in view. 
Fish culture will yield very satisfactory returns as a secondary en- 
terprise, but the site selected for the work should by all means be 
the best available consistent with the general scheme of farming 
operations. 
POND CONSTRUCTION. 
The exact mode of construction must depend largely upon local 
conditions, such as the presence or absence of favorable land contour, 
the nature of the soil, proximity to storm channels, and the area of 
the ground to be worked. Even with these features specified lesser 
local characteristics and the exigencies of individual circumstances 
will vary the application of any approved general method. Where 
practicable ponds should be not less than 1 acre in surface area. 
Those of smaller extent will produce fish and add an interesting 
feature to farm life, but they will not yield adult food fishes of the 
larger species in quantities sufficient for the requirement of the aver- 
age farmer’s table. 
Natural draws or ravines involve the least expenditure in their 
adaptation to fish ponds, as two and frequently three sides are 
already formed, so that an earthen embankment connecting them 
will complete the inclosure. Such locations must be surrounded by 
ditches to divert surface water where that is likely to roil the pond, 
and effective waste channels should be provided if the site covers 
the natural course of flood waters. 
If flat land of en elevation only slightly lower than that of the 
source of water supply is selected, it will be necessary to excavate 
the ponds in whole or in part to the required depth to insure a water 
level lower than the supply. Thus the excavations will form solid 
banks which, if impervious to water and properly sloped, will require 
no further attention except to bring them to uniform widths and 
elevation, which can be done with the material excavated in forming 
the pond proper. The bottom of the pond should be shaped to drain 
to a central point. 
On swamp lands and depressions which are susceptible to drain- 
age and are at the same time low enough to insure a gravity flow of 
water from the source of supply, one or more fish ponds can be con- 
structed by the erection of longitudinal and cross-section dikes high 
enough to provide the required depth of water. The construction of 
such ponds involves only sufficient excavating to give the bottom the 
proper slope. In other words, the pond should be built up rather than 
