40 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Some 15 to 30 minutes before the female is ready to enter the nest and spawn, 
her excitement is made evident by a change of color. Ordinarily she appears to be 
of a uniform dark olive or brown above, changing to a light green below. The only 
markings readily seen are four stripes on each cheek; but in reality the sides of 
the fish are mottled with still darker spots on the dark-olive background. The spots 
are arranged so as to form irregular, vertical bands like those on the perch, but 
these are not usually visible. Now, as the excitement of the female increases the 
background becomes paler and finally changes to a light-green or yellowish hue, so 
that the spots and bands stand out in strong relief. The whole surface of the fish 
becomes thus strongly mottled. This is a visible sign that the female will soon 
spawn. The male undergoes a similar but less pronounced change of color. 
Soon after this the female enters the nest and the male continues to circle about 
her, glide beneath her, and to bite her gently on the head and sides. At times he 
seizes her vent in his mouth and shakes it. When this has continued for a time 
spawning takes place. The two fish turn so as to lie partly on tlieir sides with their 
vents together and undergo a convulsive fluttering movement lasting 3 to 5 seconds. 
During this time the eggs and milt are extruded. The circling movements are then 
resumed to be interrupted after a few seconds by spawning. This alternate circling 
and spawning continue for about 10 minutes. The male then drives the female 
away, biting her and showing great ferocity. She does not return. 
The male, and the male only, now continues to guard the nest, fanning sedi- 
ment from the eggs and repelling enemies. At 66° F. the eggs hatch in 5 days and 
the young fish swarm up from the bottom in 12 to 13 days from the time of hatching. 
Henshall in his “More About the Black Bass,” published in 1898, quotes, with 
approval, Arnold’s observations to the effect that the nests are built and then guarded 
by the female. The Manual of Fish Culture, published in 1897 by the United 
States Fish Commission, speaks of the nests as being built by the mated fish, some- 
times working together, sometimes separately. These seem to be the latest published 
observations, and are not at all in accord with my observations in Michigan. 
Shortly after the young small-moutlied bass rise from the nest they scatter out 
over a space 4 or 5 rods across — not in a definite school with all the fish moving 
together, but as a loose swarm, moving independently or in small groups. This 
makes it impossible to seine the young fry, as upon the approach of the seine, 
instead of keeping together, they at once scatter and escape the seine. The fry 
may be at the surface or on the bottom in weeds or clear water and are attended by 
the male until they are 14 inches long. The swarm then gradually disperses and 
the young fry, which were previously black, take on the color of the old fish. 
The breeding habits of the large-mouthed black bass are similar to those of the 
small-mouthed, but differ in some respects, which are of importance in pond culture. 
1. The nests of the large-mouthed are not made on gravel, but by preference on 
the roots of water plants. These are cleaned of mud over a circular area, and on 
them the eggs are laid. As the eggs of the large-mouthed bass are smaller and 
more adhesive than those of the small-mouthed they are apt, when laid on gravel, to 
become lodged between the stones and to stick together in masses, and are then likely 
to be smothered. When laid on fibrous roots of water plants this does not occur. 
2. The young large-mouthed bass remain together in a compact school very 
much smaller than that of the small-mouthed, and the fry usually move all in the 
same direction. This makes it easy to seine the large-mouthed fry when wanted. 
