He should also give them, at any
rate after they have been feeding some weeks, a certain proportion of
natural food. Probably the best of all food for the fry is pounded
shrimps or other crustaceans. It is, however, difficult in the very
early stages of the trout's life to pound shrimps up small enough, and
the little fish are much given to trying to swallow pieces of food which
are too large for them to manage. This evil proclivity often causes the
death of the fry, and therefore great care must be taken that no pieces
of food which are too large, get into the rearing box. Pounded liver
shaken up in a bottle with water, and after the larger particles have
been allowed to settle at the bottom, poured into the rearing box in
small quantities, is a good form of food for the alevins when they first
begin to feed. The yolks of eggs boiled for about half an hour and
pounded up, dog biscuit very finely pounded, or the fine food supplied
by several of the fish cultural establishments are also excellent. In
giving moist food such as pounded shrimps, liver, meat, or the yolks of
eggs, a good plan while the fry are very small is to put the food in a
small net made of fine muslin mounted on a wire ring, and dipping the
end of this net into the water, allow small particles to escape through
the muslin. This ensures no large pieces getting into the rearing boxes.
As the fry grow larger, these precautions are of course modified, as the
little fish are capable of swallowing larger pieces of food.

With regard to natural food, the amateur should take care to ensure a
good stock for the young fish. Many of the creatures suitable for food
may be cultivated in separate ponds at the same time as the fish, if a
natural supply is not at hand. The _Daphnia pulex_ (water flea) and the
_Cyclops quadricornis_ may be introduced into the boxes very soon after
the fish have began to feed. _Daphnia_ breeds at the rate which is
almost inconceivable. The female produces her first brood of young when
she is ten days old, and goes on breeding at an average of three or four
times a month. The female and her progeny are rendered fertile by one
act of coition, probably for fifteen generations at least, without any
further intervention of the male. Both _Daphnia_ and _Cyclops_ are bred
in stagnant water in which there should be a good stock of weeds.

The fresh water shrimp (_Gammarus pulex_) is an excellent form of food
for young and old trout, and should