REARING THE YOUNG FRY. l6l 



fine, thin film of mouldy matter which could be seen 

 on the bottom was fouling the water, and I removed 

 the fish to clean the troughs. This revived them some- 

 what, and they began to eat again, but they lacked 

 their natural vivacity and looked lank and ill-favored. 

 I then began to reflect carefully on the matter, and it 

 occurred to me that their artificial food might be want- 

 ing in some tonic element, indispensable to health, 

 and that liver and curd and nothing else might be to 

 trout what olive oil and nothing else was to the dog. 

 The symptoms certainly indicated it. 



I might have got no farther, but I noticed that some 

 of the young fry, which by accident happened to be 

 where the mud was occasionally disturbed, did better 

 and appeared thrifty. I also remembered that the wild 

 trout in the natural brooks are never so lively and 

 voracious as just after the streams have been mud- 

 died by a shower. Then it suddenly flashed upon 

 me, that mud or earth, with its multiplicity of constitu- 

 ents, might possibly contain the deficient element 

 At the same time, I remembered the great absorbing 

 power of earth, which might perhaps absorb the foul 

 exhalations from the bottom, at the same time that it 

 supplied the needed tonic. 



I shared the common prejudice against muddying 

 the water where the trout were ; but the crisis was an 

 imperative one, and I determined to solve the problem. 

 I poured in earth, enough to cover the bottom half an 

 inch, making the water so thick with mud that every 

 fish was obscured with it. I watched anxiously for 

 the water to clear, to see how they came out of it. 



