REARING THE YOUNG FRY. 179 



The effect was magical. It had revived them all. A 

 change for the better was decidedly noticeable at once. 

 In twenty-four hours the sick ones were nearly them- 

 selves again, and in two days they were all better fish 

 than they ever were before. 



On another occasion large numbers of my young 

 fry had become sickly and were failing rapidly. They 

 had begun to collect against the screens, and there 

 was evidently a bad time coming very soon. This was 

 on the 5 th of March. This time they had been feed- 

 ing only about two weeks. I applied the earth plen- 

 tifully, with the same effect as before. On the 7th 

 they were much improved. On the 8th they were all 

 well again and off the screens. Earth or mud is the 

 last thing one would suppose suitable for a fish, so 

 associated in our minds with pure, clean water ; yet it 

 is an indispensable constituent in the diet of young 

 trout, and unless they get it, either naturally or artifi- 

 cially, they will not thrive. I repeat once more, we 

 are supposing the young fry to be in the hatching 

 troughs still, and supplied with water from the spring. 

 Of course, if they are nourished with brook-water, 

 which brings down more or less mud with it, this dis- 

 ease will not break out, and the fish will not require 

 the artificial introduction of earth ; but they must get 

 it in some way, and unless it is already in the water, 

 it must be furnished artificially, or the fish will lan- 

 guish.* 



I am not prepared to say what kind of earth is the 



* I have sometimes found the stomach of a wild trout nearly 

 half full of gravel. 



