82 
THE CALIFORNIAN SALMON. 
runs an inch in depth above the ova, which are distributed 
over the gravel. The gravel should be about the size of 
split peas ; if larger, the alevins burj themselves in it, and 
when they die cannot be seen, and when decaying will foul 
the water. If the gravel be smaller, when the watering- 
pot is used the shower drives it about too much, and 
buries the ova, and when any die they will produce the 
dangerous byssus, with the risk of injuring healthy eggs. 
A shallower bos than that mentioned would suit the 
hatching better, as half an inch of gravel is sufficient — the 
object of using the gravel being to retain the ova in their 
places, and to keep them from drifting about with the 
current — too much motion being injurious to them. When 
the fish are hatched, however, more depth is required, as 
the young fish soon become lively, and may jump out of 
the hatching boxes, and a deep bed of gravel is useful to 
catch and cover particles of food, or the shells and debris 
of hatched eggs. 
The hatching of salmon and trout ova, requires constant 
and extreme care and attention. Cleanliness is most 
important in everything connected with both the ova, 
and the young fish. Pure water is also of great import- 
ance, as a very slight thing may destroy a whole batch of 
eggs. In hatching English salmon, the lower the tempera- 
ture of the water during the period of incubation the 
stronger the young fish are likely to be, and 40 deg. to 
45 deg. is said to be most suitable, but in no part of Aus- 
tralia, are the streams long at these temperatures. Even 
that of the springs rising at 2000 feet above the sea, being 
about 51 deg., and unless the ova can bear much higher 
temperatures than the authorities on the subject seem to 
think possible, there is little hope of the English salmon 
succeeding in our climate. The brown trout or Salmofario, 
however, which in England is found in the same streams 
