222 
PACIFIC SCIENCE, Vol. XV, April 1961 
era ge number of worms found in these 7 6 fishes 
was 5. The largest number of worms in a single 
fish was 35. No obvious variation of the degree 
of infestation of this nematode in the manini 
was observed during the year. 
Two different leeches were found on the ma- 
nini. Both are species in the family of Pisicol- 
idae (possibly genus Johanssonia) . One is rep- 
resented by a single 2.4 mm. immature specimen 
(stained and photographed herein as Fig. 2 G) 
which was taken from the gills of an adult ma- 
nini. Six specimens of the other leech were col- 
lected from the body surface of three juvenile 
manini, 26-31 mm. in standard length, taken 
in the Ala Wai Yacht Basin on April 17, 1955. 
These leeches varied from 2.9 to 7.5 mm. in 
length, were dark brown in life, and easily de- 
tected on the host. 
Six species of parasitic copepods have been 
taken from the body surface and pharyngeal 
cavity of the manini. Lepeophtheirus dissimula- 
tus Wilson was the species most commonly en- 
countered: 112 of 164 adult manini examined 
for parasites throughout the year were infested 
with from 1 to 20 of these copepods. The other 
parasitic copepods found were two species of 
Caligus , a Dentigryps sp., Peniculus minuticau- 
dae Shiino, and Nessipus costatus Wilson, which 
encysts in the fins. A comprehensive report on 
these and other parasitic copepods from Hawai- 
ian acanthurid fishes is being prepared by A. 
Lewis. 
A mutualistic association was observed be- 
tween the manini (and other reef fishes) and 
a small colorful wrasse, Labroides phthirophagus 
Randall. In the clear water off Manana Island 
two adult manini were seen being pecked over 
the head and body by this wrasse. The manini 
remained motionless in the water except for 
slight undulation of the fins. Since the stomach 
contents of several of the wrasses consisted pri- 
marily of calagoid copepods, it is believed that 
the fish were removing crustacean ectoparasites 
from the manini. On another occasion a manini 
was observed to swim directly to the "domain” 
of two of these labrids. As the manini was ap- 
proached by one of them the surgeonfish was 
speared and brought ashore. Two adults of Le- 
peophtheirus dissimulatus were visible on its 
body. 
DISEASES 
The only data on disease were obtained from 
a series of unsuccessful attempts to maintain 
manini in an aquarium. Four adult fish were 
placed in a 23 gal. stainless steel aquarium which 
had previously been used to keep adult and ju- 
venile manini for periods of several weeks. The 
water was aerated and filtered. Two days later 
two of the fish died, and on the following day 
the remaining fish were dead. Several hours be- 
fore their death the manini swam in a dis- 
oriented manner. The fins were badly eroded. 
The head and body were excessively slimy, and 
large scattered sores were present. The fish were 
examined for parasites and found to have no 
more than the average complement. 
The tank was cleaned (but not sterilized) 
and two more adult fish added. They died in a 
similar fashion in 48 hr. The tank was again 
cleaned and a 57 mm. juvenile manini placed in 
it. This fish died just 48 hr. later. 
In spite of the filtration, the tank became 
cloudy on the second day after cleaning. A 
milliliter of the water was taken, successive di- 
lutions made, and the higher dilutions cultured 
with a sea water and agar mixture (sterile aged 
sea water, agar, and a small amount of peptone 
and ferric phosphate). The number of resulting 
bacterial colonies were counted; the bacterial 
count of the original milliliter of aquarium wa- 
ter was computed at 212,000,000. Before the 
fish were placed in the aquarium the number of 
bacteria were probably less than 1,000,000 per 
ml. 
Several smears were taken from eroded areas 
of dying manini. The dominant organism was 
a short, plump, gram-negative rod. It is not 
known whether this is the etiological agent of 
the disease or merely a secondary bacterium. 
FOOD HABITS 
Food of Larval Manini 
Only three specimens of larval manini (6.6- 
7 mm. in total length) were available for an 
analysis of gut contents. Two of these fish were 
taken in a plankton net towed between 5:46 
and 6:48 A.M. One was empty and the stomach 
of the other contained two appendicularian 
tunicates and a larval polychaete. The third fish 
