THE INVISIBLE FOOD OF FISH 



RECENT experiments on the food of the oyster show 

 that the oatmeal commonly given to fatten them 

 causes them to lose weight and die, and that flour, 

 often used for the same purpose, soon poisons them, 

 though, on the other hand, the typhoid bacillus is 

 destroyed by passing through the oyster's alimentary 

 canal. 



The latter discovery will be good news to the 

 owners of oyster beds. But the study of bacteriology 

 is a new one. What strikes the average reader as 

 more curious is the lateness of the discovery that 

 the food commonly used in shops to fatten oysters 

 disagrees with and kills them. Yet it is only one 

 of the results of what, until recently, was a very 

 general ignorance of the main food supply, not only 

 of shell-fish like the oyster, but of all the swarming 

 vertebrate fishes of the sea, except such as are entirely 

 carnivorous and live by preying upon other fish. 



The food of river fishes was better known ; but 



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