BULLETIN OF THE UNITED STATES FISH COMMISSION. 209 
not only never suffered hunger, but that they have always had abun- 
dant food of excellent quality. This kind of food, composed exclusively 
of insects and small crustaceans, is exceedingly suitable for these young 
fish on account of the large quantity of phosphate of lime which it con- 
tains; 1 and this circumstance explains the rapid growth,' and the ex- 
ceptionally fine and vigorous condition of the young trout raised at 
Gremaz. 
It may be well to add that the profitable use made of the small shrimp- 
streams will soon give way to a still simpler method of utilizing these 
small crustaceans, by proceeding in exactly the same manner with 
Daphnia , i. e ., the fish will be successively, or rather alternately, passed 
from one basin to the other, to consume a stock of food previously pre- 
pared for them. By experiments Mr. Lugrin has ascertained that a 
basin 35 meters (114.8 feet) long, and 3 meters (9.84 feet) broad, with 
an average depth of water of 40 centimeters (1.3 foot), 2 may contain 
20,000 young fish from eight to twelve months old, or 3,000 two-year old 
trout, having an average weight of 250 grams (^ or a little more than 
one-half pound). These 20,000 young fish, or 3,000 trout, consume 
about 10 kilograms (about 22 pounds) of small shrimps per day, 3 or 300 
kilograms (about 660 pounds) per month. It has been proved by ex- 
periment that a basin having the above-mentioned dimensions can pro- 
duce 300 to 350 kilograms (660 to 770 pounds) of shrimps, without at all 
interfering with the Daphnia , Nms, Limncea , insect larvae, etc., which 
simultaneously develop in the same basin. Under these conditions 
food will never be lacking. It is sufficient to have two basins for each 
lot of fish, so ms to transfer them each month from one basin to the 
other. 
The system employed at Gremaz is, therefore, exceedingly profitable 
from an industrial point of view. But it is specially destined to render 
excellent service in stocking rivers with fish. Doing away with all dif- 
ficulty as regards food, it makes it possible and even economical to 
keep the young fish, intended for stocking rivers, for a certain time in 
the basins free from all danger. Those young fish which, owing to the 
lack of suitable or sufficiently cheap food, had to be set out in the rivers 
at a very early age, before they had had time to gain strength, may 
1 It is well known that the substance which forms the skeleton of insects and 
crustaceans is, with many species, largely composed of calcareous matter, and is ex- 
ceedingly rich in phosphate of lime. It is probable that to this circumstance must 
be attributed the results of Stoddart’s experiments : “ Three lots of young trout were 
placed under absolutely identical conditions ; one lot was fed on fish, the second on 
Annelida and mollusks, and the third exclusively on insects. All the fish of the last- 
mentioned lot developed much quicker than those of the others.” In England insects 
are also considered excellent food for young trout. 
2 These are the dimensions adopted for the new basins of the Gremaz establish- 
ment, the projected enlargement of which contemplates the creation of 136 such 
basins. 
3 10 kilograms (22 pounds), dry measure, of small shrimps represent about 7 litres 
(about If pints) of liquid measure. 
Bull. U. S. F. O. 87 14 
