ARTIFICIAL PROPAGATION OF THE RAINBOW TROUT. 
245 
from the spawning-pond, being careful to put the spent females in one pond and the 
males in another, as the males are very pugnacious about this time and are not very 
particular about what they fight. 
Incubation and hatGhvm/ of the eggs and care of fry in the hatchery . — The eggs of 
trout are usually incubated and hatched on trays, which are placed in the water in 
troughs and boxes of various sizes and shapes. I prefer troughs which are made and 
set in pairs, as shown at tig. 1. These troughs are about 15 feet long, and made of the 
best pine lumber, dressed to inches thick. The bottoms are 14 inches wide and the 
sides are 8 inches wide. The guard screen (A) should be put in about 14 inches from 
^UDINO 
LONGITUDINAL SECTION OF HATCHING TROUGH, SHOWING POSITION OF HATCHING TRAYS, DAM, ETC. 
SCALE ' 
• 12 9 6 3 O 
Fig. 1. — Hatching troughs, guard screen, etc. 
A. Guard screen. E. Tin tray for use in muddy water (see fig. 2). 
B. Horizontal sliding screen. F. Block fur water to fall upon. 
C. Hatching tray. G. Brackets (fig. 2). 
D. Position of hatching traj's. H. Feet (fig. 2). 
the lower end (inside). It consists of a frame made as wide as tlie trough is deep and 
as long as the trough is wide, and put in with beveled lining on l)oth sides at the end, 
but across the bottom the lining should l)e put only outlie upper side; this will assist 
in keeping the parts clean. Instead of Avire on the guard-screen, I iirefer perforated 
tin, with perforations a sixteenth of an inch for very young fry, and larger iierforatious 
as the fish grow. The dam is put in from 4 to 5 inches from the lower end, and 
is simxily a ifiain board SJ inches w ide. In the uxpier end of my tixuighs, I use hori- 
zontal sliding screens (shown at B) Avith iierforated tin bottoms, instead of the vertical 
screens formerly used. The adAmntages claimed for the sliding screens are obvious; 
