TROUT BREEDING. 71 



they will grow to a size which will cause the troughs to be 

 overcrowded. When this occurs, those in the lower nests, 

 being the older, should be lifted out as I have already 

 advised. After those in the upper nests have been feeding 

 for three weeks or a month, the screen at the lower end of 

 the trough may be removed, and as many as are inclined, 

 or all of them, should be allowed to run down into the nur- 

 sery, or, as some call it, the u rearing-trough." It will be 

 observed by the plan that a nursery is provided for each 

 pair of hatching-troughs, and that the width of the latter 

 scarcely exceeds that of the two troughs. The reason for 

 this is that the fry may be the more easily fed, and that 

 they are more under control than if a single nursery the 

 whole width of the hatching-house was used for four or 

 six troughs. I have found the latter hard to keep clean ; 

 much of the food thrown into it is not eaten, and it 

 remains only to foul the bottom; besides, it has no current 

 and little eddies, which the fry are so partial to. The feed- 

 ing in the nurseries is the same as in the troughs. 



After all the eggs in the house have hatched out, the 

 curtains to the windows should be removed so as to admit 

 the light, and the windows and doors left open when the 

 weather is fine. Part of the roof on each side over the 

 nursery should be put on in sections, say three planks of a 

 foot wide forming a slab. Two of these slabs on each side 

 are enough. Each slab may be removed, or may turn on 

 hinges to admit the sun. Young trout delight sometimes 

 in basking in the sunshine, on shallows where the water 

 does not cover the gravel to more than the depth of an 



