Embody. — Trout Feeding Experiments 31 



This was made into a mush and fed in the usual manner. 

 After 15 days of this ration, the trout lost 8.9% of their weight 

 and were subsequently attacked by fungus which killed about 

 50% of the fish before it could be checked. 



This is a rather striking indication that the protein in peanut 

 meal is practically indigestible in the case of trout and since it 

 served no useful purpose, it was thought best to dispense with it 

 altogether. 



MORTALITY. 



The true state of affairs regarding mortality is not indicated 

 clearly by the tabulated figures except possibly in the case of 

 mixtures containing a large per cent of beef liver. During the past 

 three years of experimentation, it can be said that no abnormal 

 death rate has ever occurred when beef liver was used in mixtures 

 to the extent of 45% except where the loss could be directly 

 attributed to causes other than the food. This cannot be said of 

 mixtures containing the dried products alone. Continuous feeding 

 of these in nearly all cases eventually resulted in a high mortality. 

 The period before the mortality began varied from one to three 

 months depending upon the age and species. In general finger- 

 lings were more susceptible than yearlings and older trout, and 

 rainbow trout were less resistant than brook and brown trout. 

 In nearly all cases this high mortality could be checked in the 

 course of two weeks by changing to a diet of some fresh meat. 

 Liver, lean meat, kidney or melts were all equally effective in 

 bringing about the change. This discovery has led directly to our 

 recent practice of feeding one ration each week consisting of some 

 fresh meat alone and on the other six days using various mixtures 

 of meat meal, shrimp or fish meal, together with a small amount of 

 middlings as a binder. 



During the present year, only, have we been successful in 

 using any of these dried foods for rearing advanced fry to finger- 

 lings. In the case of some chinook salmon, ground liver and kidney 

 was fed twice daily in alternation with three daily feedings of 

 meat meal. The latter was first sifted to remove the coarse par- 

 ticles and then merely sprinkled over the surface of the water. 

 The salmon took this readily from the surface and usually cleaned 

 up that which sunk to the bottom. The total mortality from the 



