Dive Pacific 171 Oct- Nov 2019

SPECIESFOCUS
Black angelfish
~Parma alboscapularis
By Paul Caiger
Black angelfish are a charismatic
addition to any northern New
Zealand reef scene. As their name
suggests, they are black. However
they are not an angelfish, but
rather belong to the damselfish or
demoiselle family more common
to the tropics of the world. And
unlike their tropical cousins
they are far larger, up to 30 cm,
as are a handful of other Parma
species, and the Garibaldi, found in
temperate locations.
As juveniles, black angelfish are far
more colourful (see photo) and far
more like their tropical counterparts;
bright yellow with iridescent
lightning-blue dots adorning them.
Black angelfish are predominantly
herbivorous fish and live in fairly
shallow depths where sunlight
fuels algal growth. Their incisorlike
teeth are arranged into cutting
plates, perfectly adapted to nip
and shear small delicate seaweed
with their favoured types being
greens and reds. So these fish are
usually found in areas devoid of
the thicker brown kelps, some of
which is their own doing.
These fish are avid gardeners,
removing undesirable algae
and encrusting invertebrates to
encourage the growth of their
favoured food. Consequently, they
are highly territorial, a territoriality
that is enhanced during
the breeding season when males
will aggressively seek out and
defend optimum terrain. Such
terrain includes not only favoured
resources and a lack of large kelp,
but also large boulders or rocks
that include vertical rock faces
which serve as nests. In defense of
their territory, and particularly to
guard their nests, adult males will
chase off intruders, racing at them
with a strong “bark”, and flashing
a white patch on the top corner of
their gill plate. Similarly they will
happily target divers too, chasing
at any that get too close to their
nest, even nipping at stubborn
intruders.
This ability to vocalise is a trait
shared in damselfishes; black
angelfish are one of the few very
actively vocal species in northern
New Zealand reefs. In the tropical
species, sound cues emanating
from reefs has been shown to
provide orientation and settlement
cues for larvae looking for
a suitable home. It is unknown if
this is the case with Parma though
certainly very feasible.
Black angelfish are an extremely
long-lived species; up to 90 years
old! This is up there with some the
longest lived reef fish anywhere.
Remarkably too, they grow to adult
size in under two years, a factor
that permits them to put energy
into maintaining territories and
gardens, along with putting huge
investments into courting females
and protecting their offspring until
they hatch.
~Parma alboscapularis
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“alboscapularis” refers to the white shoulder
patch that flares up when excited.
Brilliantly coloured yellow and electric blue
juveniles.
Herbivorous, feeds on red and green algae.
Marine gardeners, removing unwanted algae
and invertebrates in their garden.
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One of the most vocally active fish species in
New Zealand.
Extremely long lifespan, living up to 90 years
old.
Grow to adult size in under two years.
Aggressively defend nests laid on rock faces.
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