
THE PROPAGATION OF THE GOLDFISH 

from improper feeding and other evident causes, are too much light, par- 
ticularly strong sunlight, which should be guarded against. Daily ventila- 
tion is also required, especially when the heating apparatus is in use. 
Ponp ano Lake Curture. Figs. 59 and 59a. With this method, 
the rearing ponds should not be of the same depth of water, but vary 
from 3 or 4 feet near the outlet to a few inches at the inlet, that the fishes 
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FIG. 59 Plan of a Fish Farm. 
may seek any desired depth and relieve themselves of the water pressure, 
but constructed that they may be entirely drained when necessary, and 
free from obstructions that they may be seined. Each should have 
independent inlet and outlet, but also arranged to connect in series, when 
desired. Ponds should not be formed in streams, but at a safe distance 
and the water led to them through sluices which can be closed in case of 
freshets or too muddy water. 
Each season the ponds should be drained, thoroughly cleaned and 
the upper layer of soil removed from the bottom. It is also advisable to leave 
them exposed to frost for a time to exterminate insects and other enemies. 
One or more small isolated emergency ponds, containing’ a plentiful 
growth of plants and arranged for draining, should be established; into 
which fishes may be placed in case of mishap, serve as reserve ponds for 
temporary storage, utilized for fishes of retarded growth, or for the separa- 
tion from the general stock of selected future breeders. 
A small basin dug into the soil or having a soil bottom, thickly grown 
with aquatic vegetation, to supply the water with oxygen and for the pro- 
pagation of the live food, should be arranged between the water supply 
and the rearing ponds; and if the water is derived from a spring it should 
not be too near the ponds, that it may not be of too low temperature and 
also in flowing over stones or artificially constructed ripples absorb a large 
quantity of air, as spring water is deficient in oxygen. The water of a 
shaded cold-water brook is preferable, river or pond water is not as desir- 
able on account of its rising temperature in the hot summer months. 
106 
