The Relation of Mollusks to Fish in Oneida Lake 315 
before our knowledge of the food habits of fishes is complete. 
There are many species the food of which is unknown, and 
of those species that have been given some study much 
remains to be learned. <A fact brought out in the chapter on 
“ Mollusks as Food of Fishes”? was that a species may feed 
upon a class of animals, as the mollusks, in one body of 
water and the same species may prefer a totally different 
kind of animals, as the Entomostraca, in another body of 
water. The food of the Common Whitefish in the Charle- 
voix region and in Walnut Lake is an example of this 
variation in food habits. 
It is the culture of these animals that demands the 
greatest amount of reliable information. In the past some 
of the fish culture has been haphazard, fish fry and finger- 
lings being introduced into bodies of water without knowing 
whether the natural conditions were favorable or the food 
supply sufficient and of the right variety for their growth 
and multiplication. Before a planting is undertaken, it 
would seem the part of wisdom to know the food habits of 
the fish to be introduced and the general biology of the 
aquatic medium into which the fishes are to be placed. Thus 
we should know that the body of water contains plants for 
protection and suitable grounds for breeding, food sufficient 
in quantity and of the right kind, and the presence or 
absence of natural enemies which might seriously affect the 
increase of the planted fish. In other words there must be 
as nearly as possible a balance between the vegetation — the 
fish — and the food supply. Fish will be present and will 
persist in a body of water in proportion as the food supply is 
abundant or meagre and as the enemies are abundant or few 
in number. This interrelation and interdependence of ani- 
mals, as regards their food, is illustrated by the appended 
tables showing the food of several familar fishes (see end of 
chapter). The primitive food of all animals is the inorganic 
matter in solution in the soil, water or air, which the plants 
convert into available food for animals, which are either 
herbivorous or carnivorous. ‘The microscopic plants and the 
