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 

 sac. 



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 

 can generally be distinguished from each other. 



