144 FISH FARMING I 



and any accumulation of dirt of the slightest character im- 

 mediately removed by means of a hand brush; after each 

 brushing it should be ascertained that any dirt so removed 

 is carried away by the current. The screen should be con- 

 stantly brushed, especially on the under side, care being 

 taken, of course, not to injure any alevins that may be driven 

 on to, or be resting on, the upper surface of the screen. The 

 bottom and sides of that portion of the box between the 

 screen and the outlet should also be thoroughly brushed, 

 at least, once a week ; this in addition to the daily syphoning. 

 The alevins can stand more light than the eggs, but even 

 they must have but little. I have found that frames covered 

 with common blue " veiling 1 " form excellent tops to boxes 

 containing alevins ; they exclude light and admit more air 

 than do wooden lids. 



After a time the aleving will not "pack" so much, and a 

 number of them will be found to dart and swim about the 

 whole length of the box, frequently rising to and breaking 

 the surface of the water. Then they will head up stream, 

 and the strongest of them will be found swimming against 

 the strong current at the head of the bcx some of them 

 right under the fall of water from the box above. They are 

 "coming on the feed"; and now has arrived another most 

 important stage of fish-culture. Indeed, many fish-culturist? 

 consider this to be the most critical stage of all. 



