264 
length, was observed for a period of half an 
hour at the shore of the Ala Wai Yacht Basin. 
No fish became separated by more than 12 in. 
from the rest of the group. 
The schooling of A. triostegus triostegus dur- 
ing spawning has been discussed previously. 
Reaction to Danger 
Juvenile manini along the shore of a part of 
the Ala Wai Canal infrequently visited by man 
perceive the approach of a person walking along 
the bank from an average distance of about 20 
ft. This distance is contingent on the position 
of the sun and the depth and turbidity of the 
water. The usual reaction is a swift darting to 
some immediate hiding place. If an observer 
remains immobile, the fish come out of hiding 
in from about 15 to 25 sec. and resume feeding 
shortly thereafter. Manini of the same size next 
to the sea wall of the Ala Wai Yacht Basin, 
where people pass almost continuously, do not 
interrupt their feeding at the approach of a per- 
son unless some unusual sharp movement is 
made, at which time they may hide. 
The manini in a large tide pool at Diamond 
Head were observed to have two hiding places, 
each beneath ledges at the side of the pool. One 
of these was preferred, and most of the fish 
swam to it when the pool was approached. 
When rotenone was spread in the region of this 
retreat, all of the fish swam rapidly in a direct 
line to the second ledge, in spite of the turbid- 
ity of the water (from the rotenone), even 
though they had to move in the direction of the 
observer and pass over a very shallow part of 
the pool. The part of the pool away from the 
observer was broader, deeper, free of rotenone 
at the time, but without good cover. It was 
evident that the fish were well aware of the lo- 
cation of the best places to seek refuge. 
An experiment was designed to determine 
the time required by juvenile manini to recog- 
nize and accept a new site of cover. A small 
opaque plastic bowl was inverted and placed 
with one edge elevated from the bottom of a 
23 gal. aquarium in which 12 manini, 26 to 39 
mm. in standard length, had been kept without 
a place of shelter for 3 days. Initially this bowl 
was avoided by all the fish. Fifteen min. elapsed 
PACIFIC SCIENCE, Vol. XV, April 1961 
before any fish swam near it. One hr. after the 
bowl had been added to the tank, the manini 
were frightened by rapid arm movements all 
around the aquarium; however none sought ref- 
uge in the new shelter. Upon being similarly 
frightened 3 hr. later, 2 of the smallest fish went 
into the bowl. Three hr. after this, all of the 
manini swam to the bowl for cover. 
Adult manini are less inclined to seek shelter. 
Their reaction to an approaching swimmer usu- 
ally takes the form of retreat. When cover is 
sought, the hole into which the fish swim usu- 
ally has two or more entrances. As has been 
pointed out by Breder (1949^: 97) a reaction 
to attack which alternates between flight and 
hiding is common among fishes. 
Righting 
Juvenile manini may often be seen fighting 
among themselves in the natural environment. 
Also, several days after being placed in an aquar- 
ium, this behavior becomes noticeable. It in- 
creases with time to the extent that it interferes 
with feeding. After 2 weeks in an aquarium, 
fully half the diurnal time of 12 juveniles was 
spent at this activity. The fighting was not as- 
sociated with territoriality, but took place among 
all the fish and in all parts of the tank. Three 
of the larger fish were consistently the aggres- 
sors, and the smaller fish usually bore the brunt 
of their attack, but no definite peck order was 
established. When only 2 fish were present, 
however, the larger invariably dominated the 
smaller and forced it to remain in a corner of 
the aquarium for much of the day. 
A distinct color change, which results in an 
almost complete reversal of the usual color pat- 
tern, accompanies the fighting. The broad pale 
interspaces between the vertical black bars be- 
come very dark, and the upper seven-eighths of 
the bars change to yellowish white except for a 
fine dark line in the center of each. On the 
lower eighth of the body the black bars are 
faintly visible in their normal width. The more 
aggressive fish are darker than the less aggres- 
sive ones. 
The fighting usually involves little actual con- 
tact between fish. Most of the time a fish under 
