720 BULLETIN OF THE BUREAU OF FISHERIES. 



of the ponds may be increased. The subject has not been sufficiently studied, 

 but observations so far made suggest various practical possibilities of much 

 interest. ° 



The supposed loss of young fish by the voracity of their parents induced 

 the practice of partitioning the ponds in such a manner as to confine the adults 

 in one portion while permitting the young to escape through the partitions to 

 safety. It has been found, however, that the loss from cannibalism is due 

 chiefly to the young fish themselves, and accordingly they are separated from 

 their parents or not, merely as a matter of convenience. The principal pre- 

 caution against cannibalism is, instead, the provision of an abundant food 

 supply, to divert the fish from each other. 



FOOD FOR THE ADULT FISHES. 



Food for the adult fishes is largely a matter of local conditions and con- 

 venience. Chopped fish is extensively used at some stations, and crawfish, so 

 abundant in some localities, when chopped make admirable food for the adult 

 stock. The basses, although not appearing to care for pollywogs as naturally 

 present in the ponds, will devour frog tadpoles voraciously if the latter are seined 

 out and thrown back by the fish culturist, but they absolutely refuse toad 

 pollywogs when similarly served to them. Minnows are a good food, but should 

 not be introduced into the ponds near the spawning season, as they eat not 

 only the small forms of life upon which the fry depend but often eat the fry as 

 well. Dead minnows thrown into the water one at a time are greedily taken 

 by the adult basses. 



Adult bass may also be advantageously fed on strips of beef liver about 2 

 to 3 inches long and from one-half to one-fourth inch in width or thickness; 

 and prepared food consisting of ground liver or other animal substance mixed 

 with a mush of cooked shorts, corn meal, or middlings has been employed in a 

 rather limited way. It is worthy of note that for this prepared food to be 

 attractive to bass it must ordinarily contain at least two-thirds of the animal 

 substance, whereas prepared food containing only 10 per cent of the animal 

 material is taken with avidity by trout. 



It has been quite conclusively demonstrated that one of the principal 

 causes of loss among brood fish is overfeeding, resulting in a fatty degeneration. 

 This loss has been largely overcome by reducing the food supply and at the 

 same time varying the kind of food furnished. 



ARTIFICIAL NESTS. 



In the cultivation of the small-mouth bass, and to some extent the other 

 species, it has been found profitable to provide artificial nests. These are of 



a Titcomb, J. W. : Aquatic plants in pond culture. Bureau of Fisheries Document 643. 1909. 



