§4 Modern Pishculture in Presh and Salt WateY. 



under the next one, which extends above the water line, 

 thus forcing the water downward to flow up through 

 the nest of trays and then down again. 



Fig. 2 is my system, so arranged as to secure the 

 same resuh and yet have no dams in the troughs, which 

 may be used to hatch single layers when the house is 

 not crowded. The trays should be square and of exact 

 size, only one-quarter inch smaller than the inside of 

 the trough. I have urged that all troughs be of exact 

 size inside, in order to avoid ill-fitting trays. Each 

 tray should fit any trough. Rabbet the bottoms of the 

 trays so that the wire-cloth is sunk in, for the trays must 

 set tightly on each other. Use No. 14 wire-cloth, 

 which is small and does not injure the embryos by let- 

 ting sacs and tails through. 



The top tray. A, has no eggs on it, but has a stop- 

 water, D, fast to the side, which must be put up stream. 

 The lower tray, 4, has a half-inch square strip on three 

 sides, which forces the water up through the eggs. The 

 water line is at W. To each gang of trays, four or 

 more, there must be the two special top and bottom 

 ones. The sets of trays are kept from floating up, or 

 from escape of water on the bottom, by braces across 

 the trough or by weights. In cleaning the eggs the 

 trays are floated up and one tray after another is gone 

 over. They should be picked over twice a week until 

 hatching begins, and then only once to remove shells 

 and pick out dead. The fry can be kept in these frames 

 until ready to take food, when they may be put in float- 

 ing boxes in the ponds to be fed or may be turned out. 



The capacity of a set of four trays, as described, is 

 2,500 salmon or 7,000 trout, thus increasing the hatch- 

 ing capacity of a trough fourfold and holding the fry 

 safely until the smothering period has passed. The 



