252 
PACIFIC SCIENCE, Vol. XV, April 1961 
JOO 
1 
Time 
• Fish released after capture 
* Fish sacrificed for gonad study 
Aug. I 
Sept. I 
Oct. I 
Fig. 18. Growth of Acanthurus triostegus sandvicensts. Based on 10 juvenile specimens, 25 to 27 mm. in 
length, released in a concrete tank at Coconut Island, Oahu, Mar. 17, 1953. 
dorsal black bar posteriorly on the caudal pe- 
duncle. It was found that this measurement 
could be made with greater accuracy on living 
fish than the usual standard length to the base of 
the caudal fin (i.e., posterior edge of hypural 
plate). The original measurements are herein 
retained for all tables, graphs, and discussion 
(and designated simply "standard length”), 
rather than converting to true standard length. 
Should the latter measurement be desired, it 
may be obtained by increasing the peduncular 
bar length by 3.5 per cent. 
Growth of Captive Fish 
Ten manini, 25-27 mm. in standard length 
(mean length 26.4 mm.), were placed in a con- 
crete tank at Coconut Island on March 17, 1953. 
The tank measures 34.7 X 10.8 ft. and is an 
average 3.9 ft. in depth. A constant supply of 
sea water is pumped into the tank. When the 
fish were introduced, no other fishes were pres- 
ent and the walls were covered with an exceed- 
ingly luxuriant growth of many species of algae. 
The top of the caudal fin of the 10 juveniles 
was removed to permanently mark them (see 
below ) as a safeguard against the possible addi- 
tion of more manini to the tank by other per- 
sons. 
The growth of these fishes is recorded in Fig- 
ure 18. The 3 fish captured on May 13 (mean 
length 66.0 mm.) had grown an average of 20 
mm. per month since March 17. On August 6 
all of the manini were caught (2 had disap- 
peared and 3 were killed for gonad study). 
They averaged 90.9 mm. in standard length. By 
September 27 they had grown to an average 
standard length of 94.3 mm.; thus the average 
rate of growth from August 6 to September 27 
had diminished to 1.8 mm. per month. 
The manini were caught by seining the tank 
after partially draining it. The efforts to catch 
them on September 27 failed several times, and 
much of the algae was detached from the walls 
of the tank before all of the fish were netted. 
