50 On Stocking-. 



used the term ' available oxygen/ because more or 

 less of the oxygen in the water is neutralised, or 

 imprisoned by carbonic acid given off by the trout 

 themselves, and otherwise present in the pond. 



So intricate is this question of space per 

 pound of trout live weight, that nothing but 

 practice can determine the proper stocking for 

 two-year-olds in each case ; and there must be 

 sufficient margin left for safety during a thunder- 

 storm on the hottest day of summer. If a pond 

 is so stocked as to just pass through this ordeal 

 without inconvenience, there will be no further 

 risk from over-stocking, as the trout grow larger 

 the weather becomes colder, and less and less 

 oxygen per pound of trout is required. 



In the production of pedigree two-year-olds for 

 future breeders more care is required in selection, 

 and the largest yearlings must be carefully ex- 

 cluded. One season we carefully selected the 

 largest yearlings, and the result was that the two- 

 thirds of the future breeders turned out to be male 

 fish a most undesirable result when the high cost 

 of feeding the breeders on shell-fish is taken into 

 account. Attention to pedigree and space is 

 most important; and the rule for space in this 

 case is place no more fish in the pond than are 

 necessary to consume all the food thrown in, for 

 if a pond is understocked the fish scatter, and 

 much of the food falls to the bottom and fouls 



