THE COMPARATIVE VALUE OF FOODS FOR RAINBOW TROUT 



AND OTHER SALMONOIDS. 



By CHARLES L. PAIGE. 



To demonstrate the comparative value of different kinds of food for young 

 salmonoids with any degree of exactness must necessarily entail very patient 

 and careful investigation. The fishes experimented with will have to be main- 

 tained in separate pools, under identical provisions of environment, water supply 

 and area, temperatures, and the possible supplies of natural food carried by 

 or existing in the water or in the pools themselves. Where there exists wide 

 diversity of opinion as to food values for the higher orders of animals, to demon- 

 strate the values of such atomic particles as are collected by the young fish will 

 tax the powers of the most exact scientific analyses. Any demonstration of the 

 maintenance of the fishes will in itself be subject to question as to specific heredi- 

 tary influences, climatic or aquatic conditions, prevailing habits of the fishes, 

 and many other circumstances for consideration. 



After experiments and study covering a period of many years, supplemented 

 by close observation of the fish in small areas of inclosed water, I can suggest no 

 new form of food artificially prepared superior in any respect to that commonly 

 used in most hatcheries where young salmonoids are fed. For fry I should prefer 

 these foods in the order here named : 



1. Raw beef liver, finely ground, for the first five days or week. 



2. Fresh lean meat finely groimd. 



3. Any available fresh lean meat mixed with increasing portions of wheat 

 middlings, fed either in the raw state or after being cooked as a mush. 



In the preparation of any meat food (after five or six days feeding of raw 

 liver alone to newly hatched fry) the fresh liver and meat should be thoroughly 

 ground together with from one-fourth to three-fourths of its weight of wheat 

 middlings. The middlings, in itself good food which will sustain fish indefinitely, 

 is particularly valuable in absorbing and holding the juices of meats and makes 

 a mixture of about the right consistency and gravity to remain in suspense or 

 slowly sink in water, while it is easily distinguished by the fishes once they are 



797 



