468 Fishes. 
three feet higher than the bed of the stream. From the 
middle of December to the end of January the Trout is 
in full spawning operation ; when the fish deposit their 
eggs in the hollow, and afterwards work the gravel over 
them to the depth of about three inches. If the tem- 
perature of the water is not altered during the period of 
incubation, the young make their appearance on the 
fiftieth day; never earlier, frequently later. Nature 
has endowed the young fry with so much instinct of 
self-preservation, that for many days they keep under 
the gravel, and it is curious to see the shoal hiding 
together under large stones* to protect themselves from 
danger : this they continue to do until the eggshell, in 
which they remain partially enveloped, falls off from 
their delicate frames. This shell, which adheres to them 
for fourteen days, contains a proportion of fluid necessary 
for their support during this period of helplessness. 
After this they resort to the shallows and scours to avoid 
the larger fish, where they remain solitary for a year, 
during which time, in good keep, they attain the weight 
of three to four ounces ; the second 3 7 ear, eight to ten 
ounces ; after which they begin to breed. A fish, like 
every animal, becomes fat when it has abundance of 
food with little or no exertion ; so that the growth is 
entirely regulated by the relative proportion of food and 
labour. I have observed this difference in the same 
brood of Trout, artificially bred upon my system : the 
one brood being placed in water well supplied with 
food, the other in a spring-stream where little food 
existed ; the former, at ten months old, were four inches 
long, and three and a half ounces in weight, while the 
latter were only an inch and a half long, and less than 
an ounce in weight. Although Trout are not migratory, 
yet, when they become large, they run up stream to 
purer water. The small Trout are carried down the 
stream against their habit, by the flushes of water or 
floods during the autumn months, being unable to stem 
the thickened torrent, which fills their gills with allu- 
vial deposit, and hinders their respiration, whence they 
become weak and sickly. In this state of water all fish 
sicken more or less, and it destroys vast numbers in the 
