248 PEOPAGATION OF FISH. 



is not needed for hatching purposes, as spring water in 

 these latitudes is warm enough. The house may be con- 

 structed of rough boards, or as expensively as you choose, 

 but care should be taken to have a water-tight roof, as 

 drops of water leaking through and falling into the 

 troughs will kill the eggs underneath. Its size must be 

 regulated by the number and extent of the troughs. 



The windows in a hatching house should be few in 

 number and provided with curtains or shutters, as the 

 sun shining upon the spawn will kill it. Not that a few 

 minutes' exposure to the rays of the sun will hurt the 

 eggs, but a few hours' exposure certainly will. Perhaps 

 it would be well to have the windows, if possible, made 

 on the north side of the hatching house, into which the 

 sun will not shine in the winter season. Keep the hatch- 

 ing house clean. In fact cleanliness is one of the cardinal 

 virtues to the trout raiser. He should have a clean house, 

 should work with clean hands, and have all his pans, 

 spoons and utensils of every sort free from grease and dirt. 



The troughs should be made of seasoned timber, one 

 and a half inch thick. They should be six inches deep 

 and about fifteen inches wide, inside measurement. It 

 would be better, perhaps, if the troughs were eight or nine 

 inches deep, because then the water could be raised 

 higher over the young trout after they are hatched out. 

 The difficulty in making them so deep is that when the 

 sides of the trough are made so wide, they are apt to warp 

 or stretch apart at the top, and must be stayed in some 

 way ; for instance, by strips nailed across. But the cleaner 

 the trough is of all strips, elbows, or grooves, the better. 

 The troughs are divided into squares or nests by cross 

 strips set on the bottom at intervals of eighteen inches. 



