The
Whitebarred Wrasse (Pseudocheilinus ocellatus)
So
many wrasses, so little aquarium space! Yes, I am a “wrasse”
man! This amazing family of fishes contains some of the most
spectacularly attired of all fishes. The family is the second
largest fish family found on coral reefs, with over 500 species.
Not surprisingly, its members are quite diverse in form and
behavior. The labrid family album includes everything from
Lilliputians to behemoths! Many of the smaller wrasse species are
well-suited to the home aquarium.
In
this article, I would like to examine one labrid species that has
recently been showing-up in the aquarium trade with greater
regularity. This fish, which is known as the whitebarred or
mystery wrasse (Pseudocheilinus ocellatus), has all the
characteristics of an ideal aquarium fish. It is hardy, it is
beautiful and it can be kept with a wide-range of tankmates,
including many different invertebrates. Let’s start our
examination of P. ocellatus by looking at some general
information about the genus.
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The
eightline wrasse is one of the more common members of the
genus Pseudocheilinus in the aquarium trade.
Pseudocheilinus
Tidbits
The
genus Pseudocheilinus is
comprised of seven small, colorful species. All of these diminutive
fishes are relatively secretive, remaining under ledges, in large
crevices, among rubble or amid the branches of stony corals. Because
of their small size, they are a potential target for many predators,
hence their wary natures.
Like
other family members, these wrasses are diurnal. But unlike some of
their relatives, they do not bury at night or when danger threatens.
Instead they seek shelter in reef or rubble interstices. When
stressed, these wrasses will form a mucus cocoon when they slumber.
Although data on the sexuality and mating systems of the Pseudocheilinus
spp. are lacking, there is some indication that at least one
species may change sex with a change (from female to male) in social
status.
Food
habit data is available for two species. The eightline wrasse (Pseudocheilinus
octotaenia)
feeds primarily on small crabs and other crustaceans, mollusks, tiny
sea urchins and fish eggs. The more diminutive sixline wrasse (Pseudocheilinus
hexataenia) feeds heavily on small benthic crustaceans (e.g.,
shrimp and isopods), but it also feeds on foraminiferans (which are
minute, shelled protozoa). It may also serve as a facultative
cleaner, nipping parasitic isopods and copepods off of the fins and
bodies of other fishes. I have seen P. hexataenia clean the
giant moray eel (Gymnothorax javanica) in the Red Sea and
have seen them do this in captivity on a number of occasions. The Pseudocheilinus
spp. will also eat zooplankton.
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Like
others in the genus, the secretive wrasse (Pseudocheilinus
evanidus) is a small, secretive species that is well-suited to
life in the home aquarium.
The
young whitebarred wrasse sports distinct white lines on the
side of the body. Note the beautiful markings on the head.
The
Whitebarred Wrasse (Pseudocheilinus ocellatus)
This
wrasse has been known to divers, underwater photographers and even
scientists for over a decade. It is a stunning fish that is so
different from its congeners that there is no way that it could be
confused with them. Pseudocheilinus ocellatus was originally
observed in the Coral Sea. (The first photo I ever saw of this fish
was in Randall, Allen and Steene (1990) Fishes of the Great
Barrier Reef and Coral Sea.). It was only described and received
its official scientific binomial in April, 1999. (It is not uncommon
for scientists to take a while to describe a new species of fish.)
The
colors of this fish are truly remarkable! The chromatic attire also
change somewhat as the fish matures. Young fish sport conspicuous
white lines along the flanks. These gradually become thinner and may
even disappear in the larger adults. At all sizes, P. ocellatus has
a distinct ocellus on each side of the caudal peduncle. This may
serve to deflect the attack of a piscivore from the vulnerable head
region to the tail. (Predators usually are more successful at
catching their prey if they attack the head.) The head of P.
ocellatus is a fluorescent yellow with pink tattoos! It can
reach a maximum length of around 12 cm (4.7 inches).
The
whitebarred wrasse tends to be more common around oceanic
environments, usually on clear coastal reefs or outer reef slopes.
It has been reported from the Coral Sea north to the Ryukus in Japan
and east to the Pitcairn Islands and Johnston Atoll. It is a
resident of deep reef walls and slopes, having been reported at
depths of 20 to 58 m (65 to 189 ft.). (This is one reason that this
species commands a higher price than the others of the genus that
make it into the aquarium trade!)
Husbandry:
The
whitebarred wrasse is not only magnificent in appearance, it is also a
hardy addition to the fish-only or reef aquarium. As for any member of
the genus Pseudocheilinus, it should be provided with plenty of
hiding places, like caves and overhangs. When first introduced it will
spend most of its time lurking among the aquarium decor. But once it
acclimates to its new home (which usually occurs relatively quickly if
there are no larger, more aggressive fishes in the aquarium), it will
make frequent forays into the open. I have had P. ocellatus leap
out of an open aquarium when they were being harassed by other fish.
They might also jump out of the aquarium when the lights are turned-off.
This
wrasse does not appear to be as aggressive as some of its relatives
(e.g., the eightline wrasse). I have kept it with a range of fish
species without incident, but have noticed and been told, that they
get more aggressive as they get larger. I did see a larger specimen
catch and eat small goby. Pseudocheilinus ocellatus is also
likely to behave aggressively towards more docile species introduced
after it has become well-established in its aquarium home. This
wrasse may be harassed by other fishes. For example, I have had
other wrasses chase it incessantly. I now have a smaller whitebarred
wrasse in with a Pacific red-striped hogfish (Bodianus sp.).
Unfortunately, the hogfish attacks the P. ocellatus every
time it sees it!The hogfish does not bother any of the other fishes in the
tank, including fairy wrasses and a small pinkstreaked wrasse (Pseudocheilinops
ataenia). For some reason, the hogfish hates the P. ocellatus!
This is probably due to the fact that the two fishes have a similar
shape. Many fish cue in on this characteristic when determining who
to attack! (I am now in the process of trying to remove either the Bodianus
or its victim from the tank).
An adult whitebarred wrasse.
Note the differences in color between this larger individual
and the smaller specimen in the previous photo.
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The
whitebarred wrasse will scan live rock as it searched for
smaller prey items. (Its diet is probably similar to that of the
eightline wrasse as described above.) It is a minimal threat to
ornamental invertebrates, including crustaceans. I have kept it
with several different species of cleaner shrimps without
incident. That said, I should point out that larger P.
ocellatus might eat smaller shrimp species (like anemone
shrimps in the genus Periclimenes).
When
it comes to feeding, provide P. ocellatus with a varied
diet that includes finely chopped seafoods, frozen mysid shrimp,
frozen preparations for carnivores and a color enhancing flake
food. In a reef aquarium, it will only need to be fed once every
other day as it will forage on micro-invertebrates on the live
rock. In a fish only tank that lacks live substrate, you will
want to feed it at least once a day. Once it acclimates to the
aquarium, it is an aggressive feeder that can compete with most
fish tankmates. However, make sure newly acquired individuals
get enough to eat if housed with boisterous fishes.
The
members of the genus Pseudocheilinus are well known for
their habit of feeding on pyramidellid snails (small gastropods
that are parasites of Tridacna
clams). The parasitic snails are nocturnal, spending the day
near the base of the clam or between the scutes of certain
species of clams (Delbeek and Sprung, 1994). As a result, these
wrasses are neither likely to encounter the snails very often
nor have the opportunity to prey upon them. Delbeek and Sprung
(1994) suggest manual removal is still the most effective way to
rid clams of these parasites. The Pseudocheilinus spp.
will also feed on noxious flatworms. That said, do not expect
any of them to eradicate these pests if your tank is already
infested with them!
Although
you may not see this fish at your local retail store, you can
find it on the internet at the Marine Center (www.themarinecenter.com)
and Liveaquaria.com (www.liveaquaria.com).
Happy
fish-watching!
References:
Delbeek,
J.C. and J. Sprung. 1994. The Reef Aquarium. Volume 1. Ricordea
Publishing, Coconut Grove, FL. 544 Pp.
Kuiter,
R. H. 2002. Fairy and Rainbow Wrasses and their relatives. TMC
Publishing, Chorleywood, England, 208 Pp.
Myers,
R. F. 1999. Micronesian Reef Fishes. 3rd Edition.
Coral Graphics, Guam 330 Pp.
Randall,
J. E. 1999. Revision of the Indo-Pacific labrid fishes of the genus Pseudocheilinus,
with descriptions of three new species. Indo-Pacific Fishes 28:34
Pp.
