110 Tivejity-niiifh Aiiinial Meeting 



that my surmise was correct, inasmuch as the grayling fry had two 

 fang-hke, retrorse teeth, in the upper jaw, similar to those in the 

 lake whitefish fry. This fact at once solved the problem. It was 

 imperative that they be supplied with such natural food as is found 

 only in the water of streams and lakes. 



Acting upon this hint I turned all the remaining fry into a 

 sheltered, shallow bight of the creek that flows through the hatch- 

 ery grounds. There they did well for several weeks, when they 

 sought other portions of the stream. 



In the following autumn I constructed a large pond and sup- 

 plied it with creek water by a ditch 1,500 feet in length. From 

 this pond I supplied the nursery ponds with creek water. By 

 holding a glassful of this water to the light hundreds of small 

 crustaceans (Entomostraca) could be observed, appearing to the 

 naked eye like specks of dust, and this was just what the grayling 

 fry needed, as my subsequent experience proved" 



Another desideratum to be considered for grayling fry is the 

 warmer temperature of creek water as compared with spring 

 water. They also need sunshine. While trout fry usually seek 

 the shady side of the ponds, grayling fry prefer the sunny side. 



My method is now to transfer the fry, as soon as they begin 

 to swim on the surface of the water in the hatching troughs, and 

 before their yolk-sacs are entirely absorbed, to the nursery ponds. 

 They take kindly to the change, and at once begin foraging for 

 their natural food of crustaceans, insect larvae, etc. They are 

 extremely active for such small organisms, and pursue their min- 

 tite prey unceasingly. Soon thereafter they can be taught to take 

 liver emulsion, and still later they begin to eat each other, for 

 they are as much addicted to cannibalism as the pike-perch fry. 

 The only remedy for this proclivity is to provide twice as many 

 fry as it is desired to rear, and as soon as practicable to separate 

 the larger from the smaller ones. 



*The temperature of my spring water was 45°, and of the creek water, 

 50°. The importance of creek water is not so much a matter of temperature 

 as that it contains the natural food required for grayling fry in its earlier 

 stage of existence. As a matter of course a temperature of from 50° to 60^ 

 Fahrenheit is desirable with fry of any species, in the rearing trough or 

 nursery pond. 



