5 6 1 S 9 V 11 n V n IS V '1 



Fig. 2, Graphic chart of vreight of Galician carp, Tench and Rainbow- 

 trout of lengths of from 5 to 25 centimeters, by normal nutrition. 



D. Nutrition of Pond Fish 



1. Tildes of Food 



In pond fish v/e distinguish between tv;o forms of subsistence, to wit: 



(1). Through food, sipplied by the pond itself (natural food). 

 (2). Through feeding (food supplied by the fishbreeder) , 



In the first case, the fish hvmt for food upon the "pastures" of the pond. 



The two forms can be compared to the keeping of cattle in pasture and to stall 

 feeding of them. Both forms can be made use of, in wiiich case it v/iLl lead to an especially 

 important middle form of subsistence, in carp. 



2. Natural Nutrition of Pond Fish 



Investigations upon the extent of natural nutrition of fish — \>ir tl.eir hunting for food — 

 have been ixide ir. regard to all por.d fish. An actual count of their intestinal contents is 

 the more recently prevailing method along these lines. 



A real evaluation ol the amount of subsistence, so obtained, is possible only by 

 evaluating; the nutritive value of the food consumed, i-or instance, a small Bosinlna has 

 only about the l/lOOO part of nutritive value of one middle-size larva of Chirononidae. 



Today, the iindangs of P. Schieiuenz. concerning nutritive values are generally accepted. 



He divides all natural food stuffs into the three gr..ups of: liai.n food stuffs, Occasion- 

 al food stuffs, and Emergency food stuffs, (Schaeperclaus 1928) 



10 



