BRITISH FRESH-WATER FISHES 



rearing has perhaps had something, if not a great deal, to 

 do with this. A visit to a Trout-farm is a wonderful 

 education in fish-culture, and may be strongly recom- 

 mended to those who are unacquainted with the various 

 stages that are passed through before the perfect little 

 fish has celebrated its first yearly birthday. The egg, 

 when swollen with water, is about the same size as that 

 of the Frog, but the yolk is orange-colour, instead of 

 chocolate, and the surrounding substance is greenish- 

 yellow, instead of white. 



Careful watch will reveal a perceptible change taking 

 place in the centre as the orange yolk darkens, and the 

 eyes of the little fish that is in process of development 

 soon appear. Later, there are still further changes until^ at 

 last, the young fry, or alevin as it is called, bursts through 

 its covering, with the yolk-sac adhering to its belly as 

 shown in Fig. 34. The contents of this latter keep the 

 little fellow going for some few days. Meanwhile it is 

 experimenting with its swimming capacities, and develop- 

 ing in other ways. Once the reserve food is used up, 

 however, the perfect alevin has, of necessity, to shift for 

 itself. Numerous enemies beset it, but if it survives it 

 commences to feed upon various water creatures, such as 

 insects, molluscs, and shrimps. But it takes time before 

 any perceptible increase of stature is manifest as, at a year 

 old, the young Trout has only attained a length of a 

 few inches. A year-old Trout is shown life-size in Fig. 

 36. Brook, or Burn Trout as they may be called, do 



not grow to any size, indeed many of them are not much 

 70 



