Acanthurus triostegus sandvicensis — Randall 
Following this the amount of algae on the walls 
remained slight and apparently insufficient to 
support the growth of the fish. The 5 remaining 
manini were measured again on November 19. 
They were thin, and instead of growing they 
lost an average of 1.3 mm. in standard length. 
Manini this size shrink nearly 3 mm. in stand- 
ard length when preserved in 10 per cent form- 
aldehyde solution. 
Growth Measurement from 
Progression of Modes 
The collections of juvenile manini from Ke- 
walo Basin to Makapuu Point, Oahu, plotted in 
histogram form in Figure 6 permit an estimate 
of the early growth rate by analysis of the pro- 
gression in standard length of prominent modal 
groups from week to week. By this method the 
growth rate of juvenile manini from about 26 
to 45 mm. in length is computed at about 12 
mm. per month. Particular reference was made 
to the mode which first fully appears on the 
graph on April 17. 
Growth of Marked Juveniles 
Before undertaking the marking of juvenile 
manini in the field by fin clipping, experiments 
were performed in aquaria to test the possibility 
of fin regeneration. One pelvic fin and the pos- 
terior part of the soft portion of the dorsal fin 
were cut from 3 juvenile manini averaging 27.5 
mm. in standard length. Although the fins were 
severed at the juncture with the body they 
regenerated rapidly and were nearly completely 
formed in a month. In a second experiment the 
top few rays of the caudal fin were cut away 
as well as the upper corner of the hypural plate 
to insure the removal of all fin elements. This 
cutting resulted in the permanent deformation 
of the caudal fin of the fish. 
Ten manini, 28.5 to 30 mm. in standard 
length (mean 29-2 5 ) were caught at the Ala 
Wai Canal near its entrance to the Ala Wai 
Yacht Basin on April 24, 1953. The top of the 
caudal fin of these fish was removed and they 
were released in the same area. Three of these 
marked fish were recovered, 1 on May 2 which 
measured 32.5 mm. in standard length and 2 
on May 15 which were 34.8 and 37.0 mm. long 
253 
(Fig. 19) . The average growth rate was 9.6 mm. 
per month. 
Ninety-six juvenile manini, 25-28 mm. in 
standard length (mean 26.6 mm.), were caught, 
marked, and released in a Diamond Head tide 
pool on May 10, 1953. A total of 11 were re- 
covered from this pool on three different dates 
(Fig. 19). The average growth rate of these 
fish was 12.9 mm. per month. The 4 manini of 
this group which were recovered on June 23 
ranged from 42.5 mm. to 48 mm. in standard 
length and averaged 45.1 mm. When first caught 
with the 92 others on May 10, these fish were 
a part of the prominent mode which may be 
seen centered on about 26.5 mm. standard length 
on the graph for this date in Figure 6. This 
same mode is still apparent in a sample of 147 
fish which were collected at Diamond Head on 
June 23 in an effort to recover marked fish. At' 
this time the mode is composed of 27 fish, 40 
to 49 mm. in standard length with a mean of 
43.3. Since the 4 marked manini taken on this 
date are distributed well within the mode and 
of larger average size than its mean value, it is 
concluded that the fin clipping did not retard 
the growth. 
The difference in growth rate between the 
Diamond Head marked manini and the Ala 
Wai marked fish may be associated with the 
difference in algal flora of the two areas. Algal 
growth in the latter area is sparse; it consists 
primarily of diatoms. The extraordinary growth 
rate of the captive manini in the Coconut Is- 
land tank is probably also associated with the 
nature of the algal food supply; the stand of 
algae was much greater than normally observed 
in reef or bay areas around Oahu. Invertebrates, 
including herbivorous types such as echinoids, 
gastropods, and decapod crustaceans, were pres- 
ent in the tank. It is assumed that the large 
supply of algae was primarily due to the lack 
of herbivorous fishes. When introduced to this 
unusual environment, the 10 juvenile manini 
were given an unprecedented opportunity for 
rapid growth. 
In view of the more normal environment of 
the Diamond Head tide-pool region and the 
similarity in growth rate of marked fish from 
this region to the rate computed from the pro- 
gression of modes, 12-13 mm. per month is 
