146 FISH FARMING : 



means of which the depth of water in the 17 ponds may be 

 increased as the fish advance in age and size. And this is 

 why I consider inside rearing boxes' to bs a valuable link 

 in the chain of apparatus. The depth of water in the boxes 

 may be gradually increased by placing strips of flannel across 

 the outlet spout. When the greatest possible depth has 

 been attained in the boxes, the depth of water into which 

 the fish are placed outside should only be a slight increase 

 at first on that of the water in the boxes ; this, in its turn, 

 is increased, and so on. And it will be remembered that the 

 sha.pe of the bottom of the ponds which I recommend permits 

 of the fish gradually frequenting deeper water of their own 

 accord. Do not think that I place too much importance on 

 this gradual increase in depth and volume of water. It is 

 one of the greatest secrets of success. And my present 

 advice will bs found to coincide with that given in connec- 

 tion with the management of redds, and permitting the fish 

 to gradually drop down from them into deeper water. 



The importance of strictly attending to the advice ten- 

 dered above becomes very evident when the matter of feeding 

 is taken into consideration. If a number of alevins or young 

 fry are plumped into deep water, nine-tenths of them will 

 spread out upon the bottom and literally starve themselves 

 to death's point. No amount of coaxing will induce them 

 to herd together and feed freely, as they should do. But 

 they can be taught to feed in shallow water, and then will 

 continue to do so in water that is gradually increased in 

 depth and volume. 



You may start, then, to teach fry to feed in the rearing 

 boxes, and as soon as they come well on the feed they should 

 be transferred to water in the open. This should be not 

 more than a fortnight after they first start to take food. Be 

 very careful at the time of transfer that the temperature 

 of the water into which the fish are put is exactly the same 

 as that from which they are taken, and, should this entail 

 much adjustment, let the work be done very gradually. 

 Sudden change of temperature however slight spells 



