A shoal of
Zebrasoma
desjardinii
harassing territorial
Acanthurus
leucosternon pairs,
which initially
defend their
territories…
something edible to be found
everywhere.
But everywhere I also saw
a huge variety of damselfishes,
other pomacentrids, and even
small Star-spotted Groupers
(Epinephelus hexagonatus), who
took exception to all this and
let fly at the invaders. Hence
feeding stops were invariably
very brief, at most 8–9 seconds.
Anyone wanting to remain with
the shoal had to hurry and keep
up diligently; the surgeonfishes
waited for no one, although
now and then I had the impression that they felt more secure
in my immediate vicinity. Were
the damselfishes perhaps somewhat less ferocious there?
As I watched the close-packed throng of mixed surgeonfishes, it seemed to me that
the statements made by many
authors were quite beyond belief—for example, De Graf in
1977: “…there are often disputes within the school, above
all when two individuals come
too close to one another…”
I have never been able to observe this, not even a hint; the
idea may well be attributable to
aquarium observations.
As an aside: Pacific Trumpetfishes (Aulostomus chinensis)
utilized large feeding shoals as
camouflage, albeit only those of
Convict Surgeonfishes. Now and
then they came across another
potential companion, specifically me, and then wavered undecidedly to and fro several times
between the shoal and myself. If
I moved too far away from the
shoal, they hastened back to the
Convict Surgeonfishes.
The most impressive background sounds were produced, as one might expect, by parrotfishes! Even when they are traveling alone they make an astonishing amount of noise, and their
powerful bites on huge corals leave behind impressive traces of their presence. A feeding shoal
of adult parrotfishes behaves really boorishly and veritably “thunders” through the area! One
can no longer hear the individual biting sounds, just a wall of sound composed of cracking,
splitting, and breaking noises that then moves on. Usually it is possible to recognize only the
outlines of their enormous, broad-backed bodies, as their activity stirs up clouds of sediment,
and small pieces of coral and sand also blur the view. They weren’t at all bothered by my presence—in my vain attempts to get a better view of their feeding orgies I squashed myself into their
