EEAEINa YOUNG TEOUT 169 



are naturally the easiest to cleanse, and those 

 ■with natural banks the hardest. To clean con- 

 crete or tile ponds the water-supply is first shut 

 off and nearly aU the water is allowed to run 

 away. Before the drawing, a quantity of salt 

 should be dissolved and the brine thrown into 

 the water, so as to loosen slime and other refuse 

 that may be deposited on the bottom and sides. 

 The salt will at the same time act as a health 

 bath for the fish. When the water has been 

 drawn off as far as safety will permit, the sides 

 of the pond are thoroughly swabbed with a 

 brush and the dirt and refuse worked to the 

 lower end to the outlet, where the current will 

 carry it away when again turned on. To clean 

 large ponds contaiaing mature fish draw the 

 water down, clean the sides with a brush, and 

 then allow the full current of water to run 

 through the ponds. 



Sorting. — Trout, like other carnivorous fishes, 

 are cannibals, and in a wild state the death- 

 rate from this cause is large. Partly for this 

 reason the trout in the ponds ought to be sorted 

 into sizes as soon as possible. When first in- 

 troduced into the nursery-ponds as advanced 



