Trout Breeding. 8l 



of the trough and working it down. This requires to 

 be attended to much oftener when some distance below 

 the spring, as all disturbance above tends to foul the 

 water and the flow in the trough is not strong enough 

 to carry it through. A box with the bottom knocked 

 out, and a fine sieve substituted, is good to fasten above 

 the pipe to keep leaves and coarse particles out. 



In the hatching house the use of gravel is nearly 

 obsolete, although Mr. Frank N. Clark, a veteran fish- 

 culturist of acknowledged ability, has recently returned 

 to its partial use, as has been told in these pages. 

 Frames, with wire bottoms, are used, as described 

 under that head. The frames are often placed one 

 above the other to the number of five or six, thereby in- 

 creasing the hatching capacity of the trough as many 

 times, and rendering the cleaning easily and thoroughly 

 done by raising the frames, sprinkling them with a 

 common watering pot, and washing out the trough with 

 a small broom ; with this system no strips are used, but 

 for simple experiment the gravel will do, it being the 

 old system under which we worked for years before the 

 introduction of the frames. But while five or six lay- 

 ers of eggs may be developed, these should not be al- 

 lowed to hatch in the trough or the young would be 

 smothered. 



A trout egg requires 60 to TOO or more days to hatch, 

 according to temperature, and the colder it is, down to 

 freezing, the longer it takes. Warm water, 60 Fahr. 

 and upward, hatches them quickly, but leaves the em- 

 bryos weak and liable to die. After hatching, the water 

 in the trough may be deepened and the current slightly 

 increased ; the strongest of the fry will work up stream 

 and the weaker will try to hide or be carried against the 

 screen, where they will finally be suffocated by the 



