58 MARVELS OF FISH LIFE 
over, both fish, emaciated by their long fast and ex- 
hausted by the exertions of spawning, slowly drop down 
into deep water, and return to the sea early in the 
spring. 
In due course the salmon alevin hatches, and at the 
end of five or six weeks this larval fish loses his yolk 
sae. 
After the yolk sac has disappeared, as in the case 
of the trout, the alevin becomes a fry. By the autumn 
these fry have grown to two or three inches in length, 
and are then known as parr. 
Salmon parr, trout fry, and the young of sea-trout 
are to be found in the shallow water of most salmon 
rivers, but they are not gregarious, and one young fish 
will resent the presence of another by nibbling his tail 
or some other part of his body. 
These little fish when two or three inches in length 
are brightly coloured, and objects of great beauty. Each 
has a dark olive back, sides of the same colour, but of 
a lighter hue, and glittering white under-parts. The 
dark olive colour of the back is continuous at regular 
intervals with the vertical bars or parr marks across the 
lighter sides of the young fish. On the top of this 
variegated colour arrangement is seen a metallic irides- 
cence of gold and silvery hues, and the sides are also 
freely spangled with black and crimson spots. 
Though very similar in appearance even at this stage, 
the salmon parr, the trout fry and the young sea-trout 
ean generally be distinguished from each other, 
