152 American Fisheries Society 



minute alga, Dictyosphaerium. While these observations show 

 that the daphnids may derive their food supply for a more or less 

 continued period on a single type of alga, provided it is abundant 

 enough, it is found that an assortment of plant material in a fresh 

 or partially decomposed state may be wafted into the food stream. 



The mayfly and caddisfly larva? which contribute to the food 

 supply of young fish are largely herbivores, while the dragonfly 

 and the damselfly larvae, beetles, etc., are primarily carnivores, 

 feeding on animals whose food in turn, however, is vegetable. 



In this consideration of the dietary of young fish, I have 

 emphasized particularly the algal resources of the ponds. I have 

 omitted reference to the contributions of the larger aquatic plants, 

 the potamogetons, the myriophyllums, water-weed, Chara, 

 etc., not because there is no evidence to produce in their favor, but 

 because propaganda in this direction seems less necessary. There 

 exists already among fish culturists a wholesome respect for their 

 presence in the ponds. The algae have not fared so well and must 

 be considered in providing an abundant supply of natural forage 

 for the young fish. 



