S6 Modern Fishculiure in Presh and Salt WateY. 



Filters. — If filters are necessary they may be made 

 in wide troughs with coarse wire screens at the upper 

 end and finer ones below, ending in cheese-cloth or flan- 



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ao FeEJ 



Plan of Hatchery with 12 Troughs ; capacity 30,000 each in 

 single layer. A, sink for washing; B, closet; S, stove; 

 WW, windows. 



nel. Or the water may flow through sand and gravel, 

 according to the nature of the material to be filtered out. 

 There should be a screen at the head of each trough to 

 prevent stoppage at the outlet. 



CHAPTER III. 



TROUT EGGS. — ^DISTINGUISITTNG SEX IN FISHES. 



It is with the fishes as with the birds : some species 

 show sexual diflferences at a glance at all times, some 



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