73 
tificial food and growth we must for the present disregard, 
or assume as constant, the initial vitality, natural food, 
range and space. 
For convenience of study I have adopted as a unit ‘‘ the 
average daily rations in pounds per thousand yearling 
trout.’’ I am aware that the unit would be more expres- 
sive and exact if it were based upon the number of pounds 
of fish rather than upon the number of fish to be fed. I 
have the data of the amount and character of food and 
rate of growth of the fish at sixteen trout-cultural estab- 
lishments in the United States and Great Britain, the 
régime and results of which may fairly be assumed as typi- 
cal of fishculture in general. These data present the as- 
tounding variation in the daily rations per thousand year- 
lings of from 2toz. of animal (or flesh) food, in ponds 
containing very little natural food, to 101bs. of animal 
food in ponds abounding in natural food. I have calcu- 
lated the weight of one thousand of the average yearling 
trout raised at these places to be 52.75 lbs. and the average 
daily rations to be 34 lbs. In other words, the average 
allowance for yearling trout is 64% of their weight. This, 
it seems to me, is out of all proportion to their necessities, 
and certainly is not warranted by analogy. It is true, as 
before pointed out, that the rate of growth depends to a 
large extent upon the location of the hatchery, and the 
corollary follows that the food allowance will also vary 
with the location. The allowance of a hatchery in a warm 
section cannot be considered a guide for one in a colder 
or more elevated region. For instance, trout reared in the 
Ozarks acquire a weight 700% in excess of those grown in 
the mountains of Colorado. The Colorado trout could not 
consume the allowance of the Ozark trout, and the Ozark 
trout would stunt or starve on the Colorado allowance. 
On this subject Mr. Stone says in ‘ Domesticated Trout”’ 
(page 236): “The quantity [of food] varies with the sea- 
son, the quality, quantity and temperature of the water, 
