300 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
be found in tlie fact tliat theii' progenitors, spawning them at 2 years old, were raised 
on the same diet. As yearlings these fish averaged G inches long and 51. 8G pounds 
to the 1,000 fish. 
The adaptability of the stomach of the trout for various foods was tested by the 
following experiment which I conducted at Neosho in 1892. On August 9, 1892, 
12,000 healthy trout fry, which had up to that time received the same geueral treat- 
ment and allowance of food as we usually give, were deprived of all animal or flesh 
food. From that time until they were shipped, in February, 1893, not an ounce of 
animal food was given them, and it is certain that tlie natural animal food which they 
might have obtained was the very least. At the end of the year they averaged 4 
inches in length, and an average 1,000 weighed 27.5 pounds. The fish were normal and 
healthy, and though under the average for Neosho, they were above the average of at 
least two American establishmeids. 
The results to be obtaiiied bj^ this method are intimated above and a comparison 
of results may be made by referring to the table on page 295„ 
As to the cost of this method the following table show's the allowance per 1,000 
fish from May 1 (about the average time wlien fry are liberated as such) to December 
31. I might state tliat at the Neosho Station liver costs 5 cents per pound and mush 
one-fourth of a cent per pound. These prices will, of course, vary with the locality. 
Daily allowance of food, in. pounds, per 1,000 rainbow trout {Keosbo method and praGtice). 
Period of time. 
Liver. 
Mush. 
BuiingMay 
. 07 
.30 
Juiift 1 to 7- 
. 10 
.40 
June 8 to 14 
.12 
.48 
June 15 to 21 
.15 
.60 
June 22 to 28 
. 17 
.68 
•June 29 to 30 
.20 
.80 
.July 1 to 5 
.20 
.80 
July 6 to 12 
.22 
. 88 
•J uly 13 to 15 
.25 
1.00 
J ul'y 20 to 26 
.27 
1.08 
July 27 to 31 
30 
1.20 
August 1 to 31 
.30 
1.20 
Se])tember 1 to 30 
.35 
1.40 
October 1 to 31 
.JO 
1.60 
November 1 to 30 
.4,1 
. 1.80 
December 1 to 31 
. 5C 
2.00 
Calculations from the above table show that the food for 1,000 rainbow trout from 
May 1 to December 31 (discarding fractious in the totals) amounts to 75 iiounds 
of liver and 300 pounds of mush, costing in the aggregate 14.50. The production 
for this expenditure averages 50 pounds of trout. The value of this product varies 
with the market, and is impossible of calculation for any specified period. 
In a short article in the United States Fish Commission Bulletin for 1894, pp. 71 
and 72, may be found some additional notes on the feeding and rate of growdh of 
trout in their second year at Neosho. By reference to this article it will be seen that 
1,500 13-months-old rainbow^ trout made tlie remarkable gain of 241 per cent of their 
weight in ninety days at an expenditure of 5 cents for food for each pound of trout 
gained. At the end of sixteen mouths these fish were at the best marketable weight, 
about one-third of one pound, secured at a cost, for food, of about 7J cents per pound 
of fish. This very rapid development of the trout during the latter three months is 
not peculiar to Neosho. Sefior Chazari states that the rainbow trout in Mexico attain 
a weight of IGO pounds per 1,000 yearlings ( ! ), and that ‘‘their development in the 
latter part of the year is very rapid.” 
