The pond manager uses the food-quotient in order to calculate relatively, the price 

 value of a food. The food quotient is the figure which indicates how many weight units of 

 food are required to produce a weight unit of fish growth. The older expression food 

 coefficient means the same as food quotient. Since the calculated figure ia not of invari- 

 ably constant size, but as shown below is a highly variable ratio figure, I consider it 

 more correct to speak not of a "Coefficient" but rather of a "Quotient". The food quotient 

 pennits Judgement of the commercial value of a food. 



In carp culture, the food quotient is easily determined by dividing the amount of food 

 issued through the increase of natural food in the ponds. The so calculated figure is the 

 "absolute food quotient" (Walter). 



Unfortunately, some fishbreeders are still accustcmed to figure out the food quotient 

 according to the formula of: Food plus increase through fertilization - or - Food plus 

 fertilizer plus increase in natural food. The food quotient so aridved at, is spoken of 

 as "relative food quotient". 



In order to avoid misunderstandings I wish to point out that in this book the "absolute 

 food quotient" is meant whenever the word is used. 



It must never be forgotten, that the "absolute food quotient" in the carp-pond flsheiy 

 is only a commercial measure and does not express the purely physiological activity of a 

 food. In its calculation the individual losses of fishes are neglected. Besides, as I 

 repeatedly emphasize, a stronger evaluation of natural food results from the stock increase,, 

 due to feeding. The height of the food quotient for a food depends also on the kind «rf 

 stock* 



In trout feeding in intensive operations, the food quotient is determined simply by 

 dividing the weight of dispensed food by the total growth weight,' Since the trout in the 

 feeding pond take up additionally, only relatively small amounts of natural food, the 

 resulting error here is not all too large. Besides, it is partly offset by the neglect 

 of the losses. 



Above and axiay from the sum total sources of error, even the "physiological food 

 quotient" for one and the same food is no completely fixed unalterable size. Theoretical- 

 ly, it could be assumed that it depends on the size of the fishes because the ratio of 

 maintenance food requirement to growth food requirement would not be constant in various- 

 ly sized fishes. Cornelius, however, has found no differences in food quotients in 

 various sizes of rainbofw trout. The food quotient for the same food was appraximately 

 equal for brood weighing 100 milligrams each, and for fingerlings weighing from 5 to 100 

 grams. 



On the other hand, Cornelius found that with trout there exists a dependence of the 

 food quotient upon the temperature. Furthermore, according to Cornelius, the food 

 quotient drops as the oxygen content increases, until it reaches the lowest value at an 

 oxygen ccntent of 17 milligrams per liter. The food quotient of a food for every kind 

 of fish naturally also depends upon the health status of the fishes (gyrodactylusl) and 

 upon the kind of feeding, Cornelius found that with rainbow trout, the food quotient 

 requires at least a thrice daily feeding to reach the same value given by uninterrupted 

 availability of the food. 



TOiich brings us to the conclusion that the food quotient of a certain foodstuff and 

 for certain kind of fish is not to be considered as generally characteristic and invari- 

 able . The food quotient depends upon the biological conditions of the pond, upon various 

 environmental factors , upon the modus operandi of feeding and upon the general conditions 

 of the fish . 



The influence of the foodstuffs themselves upon the rate of the quotient is explained 

 by the varying caloric values of the divers foodstuffs. The desirable rate of the quot- 

 ient will be discussed later. 



I»tTH09 



132 



