752 THE POPULAR SCIENCE MONTHLY. 



lected worm hole or nail hole. Their persistence in getting out 

 of the place where they are put is wonderful. 



When the fish are about six months old, say in September, 

 they are taken out of the baby ponds, assorted in three or four 

 sizes, and put in the yearling ponds, where they remain until the 

 following year, when the largest are sent to the breeding ponds. 

 At the same time the water is lowered in all the ponds, and they 

 are thoroughly swept out preparatory to the taking of spawn, and 

 the fish are not again disturbed until spring. The breeding ponds 

 are cleansed in this way in midsummer, but all are daily gone 

 over with long-handled nets to remove the ordure and any un- 



When a Large Trout Struggles. 



eaten food ; the screens in the baby ponds are not taken out, but 

 are cleaned with brooms or a scrubbing brush on a handle. 



The breeding ponds are best if about sixty feet long, fifteen 

 feet wide, and from two to three feet deep. In such a pond from 

 one thousand to four thousand trout of half a pound may be kept 

 if the flow is sufficient. If the supply of water is scant in sum- 

 mer, make the pond narrower or shallower, in order to give a 

 quicker change to the fish. 



Each breeding pond must have a spawning race at its head, 

 and these are narrow and shallow, making an ideal place for a 

 trout to deposit its precious burden. They are from twenty-five 

 to fifty feet long, two to three feet wide, with water from five to 



