Hayford. — Trout Feeding Experiments 253 



and that the troughs in which they were confined were divided 

 by wire screens into three compartments, each compartment con- 

 taining 100 fish, or a total of 300 fish per trough. The object 

 of the screens was to provide a more equal distribution of the 

 food. The troughs containing the brook trout were not so di- 

 vided, and only 100 fish were allotted per trough. With this ex- 

 ception all of the fish were held in environment identical in all 

 respects ; the only point of difference was the variety of food 

 supplied. The brown trout were considerably smaller than the 

 brook trout. 



Among the more pronounced points developed from a study 

 of the tables are the wide variations in mortality and growth, 

 brought about, it seems fair to assume, by the different varieties 

 of food. Sheep plucks at 5 cents per pound seem to be entitled 

 to first consideration, while beef livers at 13 cents per pound, 

 and perhaps quite generally considered one of the best of fish 

 foods, is only a poor second. The fly larvae or maggots also 

 produced very satisfactory results. 



Water temperature throughout the course of the experiment 

 was unchanged at 51° F. or 28.3° C, and the percentage of 

 hemoglobin remained constant in all cases, regardless of the kind 

 of food used. The insect forms of food were: Corixse; black- 

 fly larvae ; and Mayfly and stonefly nymphs. 



The difference in results obtained from feeding the various 

 foods to fish of different ages is surprising. When the fish are 

 two or three months old they seem to do well on certain foods, 

 and at five or six months they do better on other foods. This 

 goes to show that in order to obtain successful results, we ought 

 to administer a balanced ration. We blame many of our 

 troubles to the temperature of the water, and other things, 

 whereas it may be that the difficulty is caused by a lack of vita- 

 mines or something that we can furnish. 



