(Bulletin of the U. S. Fish Commission, 1887, p. 203.) 
SELF-REPRODUCING FOOD FOR 
YOUNG FISH. 
By Frank H. Mason, Consul. 
-Every person who has been interested in the artificial 
propagation of fish, and particularly trout and the sev- 
eral other species belonging to the genus Salmo, knows 
what care and labor are necessary to carry the young fry 
through the period immediately following the absorption 
of the umbilical sac, and to bring them to such a stage of 
maturity that they can be safely turned loose in open 
ponds or streams to shift for themselves. The mere 
hatching of the eggs involves no difficulty, and, under 
fair conditions, is ordinarily so successful as to make the 
propagation of fish in almost any quantity an apparently 
easy matter. But with the commencement of artificial 
nutrition the serious part of the task begins, and it is. 
usually a small percentage of the swarms which are 
hatched that reach the maturity of yearlings, at which 
period the dangers of infancy are past. During the 
intervening months it has been customary to feed the: 
young alewives on curdled milk, coagulated blood, finely-- 
hashed meat and liver, grated yolk of eggs, macerated 
brains of animals, etc., the preparation of which, and the 
frequent feeding of the dainty little creatures, involves. 
constant and more or less costly labor. Moreover, none 
of these forms of nutriment have been found entirely 
satisfactory, for the reason that they are all distinctly 
artificial and different from the living, organic food. 
which nature provides for those species of fish during 
their tender, infantile period. The difficulty of provid- 
ing proper nutriment results often in turning out the 
young fry into open water too early, when the tem- 
perature of the stream or pond is so much below that. 
