It is for this reason that the metabolic rate of a small sized carp of 12 grams 

 (in 24 hours and per kilogram body weight) is 2A.^S kilogram-calories, as against 7.97 

 kilogram-calories of a fish of 600 grams weight but of less proportional body surface. 



Upon a basis of 1 square decimeter of body surface and at a water temperature of 15 

 degrees centigrade, we find that the caloric needs of the small-sized carp amount to 27 

 gram-colories, as against 23 gram-colories in the larger fish. 



Therefore, we must not lose eight of the fact that in fish small differences in length 

 mean nevertheless ^eat differences in caloric requirements » 



Evidence for the relatively greater caloric needs of smaller fish — per weight unit — 

 is their greater oxygen consun^tion per like weight. 



Therefore, if the holding capacity of containers for transportation is figured upon 

 the basis of weight, such containers must carry less fish weight in smaller fish than in 

 full-sized ones. 



Far too little attention is paid to the fact that other essential metabolic functions— 

 reproductive anabolism. for instance, are relative to the size of fish. 



The rate of growth, by sufficient feeding, is the more rapid the smaller the fish. 

 The age of the fish, in this respect is apparently of little importance. 



Making an experiment with some carp, A summers old, impeded in their growth, at the 

 hatcheries of the Forest Academy in Eberswalde, I observed a weight increase from 277 

 grams to 1300 grams. Two years previous to tliis, carp, 2 summers old from the same spawn, 

 in the same pcwid and under identical conditions merely increased from 285 grams to 9-40 

 grams. 



The beginning of full maturity (puberty) seems also to depend upon size, rather, and 

 not upon age alone. Buschkiel reports that carp in India reach the stage of full maturity 

 (ability to propagate) at as early an age as 1 to 1^ years, as against the age of 3 or /i 

 years in Germany. Nevertheless, the faculty of propagation is strongly influenced by age. 



I have observed, myself, tench females of only 7 centimeters length — retarded in 

 growth through malnutrition — fully mature and able to spawn. As a rule, such females will 

 begin to sp>awn only after having reached a length of from 18 to 20 oentimeters. 



The existing relations between the demands for grovrth increase and the demands for 

 mere sustenance are very in^ortant from the practical viewpoint, especially among the 

 different full-sized fish. The rate of the food-quotient is based upon it. 



But the favorable food-quotient of yearling carp in comparison vdth full-sized carp 

 cannot be used for the solution of this problem. The lower quotient in this case is 

 chiefly due to greater utilization of natural means of subsistence on account of increased 

 density of population. 



Quite recent observations by Cornelius . upon rainbow trout, of from 100 milligrams to 

 100 grams in weight, did not shov/ any differences in the food-quotient. 



Schaeperclaus (1928) calculated the ratio between demands for growth and demands for 

 sustenance — in young rainbow trout in proportion to their weight . He arrived at the 

 figures of frcm 1:1.5 to 1:3.2, vAiich may be regarded as an average for most pond fish. 



It is generally known that the total calorie needs, and consequently the oxygen 

 requirements depend upon the kind of fish. The following figures by Lindstedt. calculated 

 upon 1 sqiiare deciiaeter body surface, per hour and for a temperature of 15 degrees centi- 

 grade may be considered as more or less correct: 



