1012 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [4] 



serts that carp, from their third year, live principallj" on fresh and de- 

 caying vegetable matter. This is contradicted by the experience that 

 they are easily raised in ponds which contain but few plants, and by 

 the circumstance that, if aquatic plants formed the exclusive, or even 

 principal foo<l of carp, vegetation would, in some ponds, be utterly 

 destroyed in a few days after they had been stocked with carp, or at 

 any rate in a couple of years, as carp are particularly fond of young 

 shoots, which, by the way, show a pretty close proportion of nutritive 

 matter. Such an occurrence, however, I have never yet been able to 

 observe, nor has it been observed by any other pond-culturist ; whilst, 

 on the other hand, it has frequently been observed that in carp-ponds 

 vegetation becomes so rank and luxuriant that it has to be checked. 

 As long as decaying vegetable matter has not been examined as to the 

 quantity of nutritive substances contained in it, no opinion can be 

 formed as to its suitableness for carp food. 



My own observations have taught me that the carp only takes to 

 vegetable food when absolutely no animal food can be procured. I 

 have not yet been able to ascertain whether the carp actually eats and 

 digests decaying vegetable matter, because all I have so far been able 

 to observe has been that the carp often swallows such matter, but 

 almost immediately ejects it again, perhaps after having devoured 

 •worms and insects clinging to such matter. 



When I began to make the attempt to fix a standard of food, based 

 on the analogous theory of food of land anim.ils, but keeping in view 

 the difference in the nature of fish and these animals, my object was to 

 provide some aid to pisciculturists, and more especially to carp-cultur- 

 ists, in the artificial feeding of fish, so as to enable them, to some extent, 

 to calculate results; and as this standard is not intended to furnish 

 anything but such an aid, it is not necessary, in mixing food, to be ab- 

 solutely exact in observing the quantities given by me, as, in mixing 

 the food of domestic land animals, such exactness is not essential. The 

 quantities should, however, approach those given by me, and it would 

 be wrong to increase the proportions three or four fold. Even if such 

 an increase (presuming there is a sufficient quantity of albumen) might 

 not affect injuriously the nutritive quality of the carp food, it would at 

 any rate involve a waste of hydrates of carbon, which, when they have 

 to be bought, make the food more expensive, and will more or less de- 

 crease, or even entirely do away with the revenue. More than a 

 hundred observations as to the food and feeding of carp, made by me 

 in my piscicultural establishment, have proved to me the apj^roximate 

 correctness of my standard of food, but have also shown that the 

 quantity of nutritive matter per 1,000 pounds of live carp, might be 

 less than has generally been supposed. 



Calculations made on the basis of my standard of food and given in 

 my Lehrhuche der Teichwirfhschaft, p. 219, showed that 1 kilogram of 

 meat flour [FuUcrflehchmelil)^ which contains 0.602 kilograms of digest!- 



