314 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
has not only lost much of its shyness, but by adapting itself to our circumstances 
has become a fish very closely resembling the German brook trout, and is particularly 
well adapted to artificial culture. 
Our fish-culture, however, would hardly have reached its present height, if we 
had not adopted the two Americans, the char or American brook trout ( Salmo 
fontinalis ) and the rainbow trout ( Salmo irideus). They must be considered as of 
primary importance in fish -cultural establishments. They will never crowd out our 
brook trout but will maintain a place in the public favor. The char, wherever it is 
known, already fetches a higher price than the brook trout; and the rainbow trout, 
which, owing to its enormously rapid growth, easily becomes too fat, finds a ready 
sale as a three-year-old fish, weighing from 1 to 3 pounds. 
At Sandfort and several neighboring establishments a ready market has rapidly 
been created for all the above mentioned kinds of trout. When sold at the ponds 
they fetch the following prices: Brook trout, rainbow trout, and char weighing one- 
fourth to one-third pound, 3 to 44 marks per pound (71 cents to $1.07); large rainbow 
trout, ill marks (59 cents). The last mentioned price pays better, as regards large 
fish weighing 3 to 5 pounds, which require but one young fish for raising, than 3 
marks (71 cents) for fish weighing one-fourth pound, where four are required to make 
1 pound. It is, of course, not possible to procure in every locality sufficient space for 
raising trout as large as that; in comparatively small ponds the fish will not reach 
such a weight in three or four years, even if there is an abundant supply of fresh 
water and very ample food. 
Fish need, as they grow older, more space and greater depth of water. At 
Sandfort, therefore, the two-year-old rainbow trout which have outgrown the desired 
weight and weigh about half a pound are (to the number of GOO or 700) placed in a 
pond having an area of about 1§ acres and a depth of water of 6 feet, and there reach 
during one more year the weight of 3 to 4 pounds per fish. It is probable that the 
same result could be obtained in a smaller pond with a greater depth of water; at any 
rate, 1,400 fish averaging 4 pounds are, from one year to the other, kept in Scotland 
in a pond having an area of 30 by 70 meters (98.4 by 229.6 feet) and a depth of 4 
meters (13.1 feet). 
It will be useful to get a proper idea as to the quantity of food required per year 
in a trout-raising establishment of average size and to learn the cost of intensive 
artificial culture as compared with extensive natural culture. It should be remembered 
that trout are very settled in their way of feeding and that it is difficult to accustom 
them to a change in the color and consistency of the food. It will therefore be useful, 
from the very start, to select such food as can be obtained regularly and when mixed 
can be steadily given to the fish. It is true that it does not hurt the trout to fast for 
a few days, but regular feeding is nevertheless one of the conditions of success. 
Trout-raising establishments should, with the view to facilitate the sale of the 
fish, not be removed too far from the great highways, and if this condition is fulfilled 
it will also be easier to obtain food. 
Salt-water fish make excellent food for trout and can be obtained regularly and 
cheaply; and these, with the refuse from the slaughter-house, must be principally 
relied on. 
The fish-auctioneers at Hamburg, Altona and Geestemlinde will gladly indicate 
the sources from which salt-water fish can be obtained. It is best to take such as are 
sold with the blood and entrails, as the sea scorpion and cod ; herring are generally too 
