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Introduction
The moray eel family (Muraenidae) contains quite a
number of extraordinary fishes from the tiny yellow Dwarf moray
(Gymnothorax melatremus) to the impressive Tesselata eel
(Gymnothorax favagineus). Some eels command high prices in
trade, not because they are exceptionally rare in nature, but also
because the young are often very secretive, difficult to catch and
because the transport of larger animals is more expensive. Sometimes
the reputation of a species as a status symbol may also be related to
its pricing. Aside that, the Hawaiian dragon eel Enchelycore
pardalis has a number of characteristics interesting to hobbyists
as well as divers and photographers: A fierce look with long pointed
teeth and a long snout that cannot even be closed completely apparently
due to the teeth. Very few other moray eels exhibit orange and red
colors, and none does in such intensity. Enchelycore pardalis reaches up to 3 feet
(92 cm). The funny looking tubes above their eyes reminding of dragon
horns are simply their rear nasal tubes. Water enters the eel at the
shorter frontal nasal tubes on the tip of the snout, streams through
channels with large folded surfaces for smell and leaves through the
rear tubes. This structure explains why eels have such a good sense of
smell. The rest of the features is pretty much moray eel standard. A
long muscular body, a think slimy skin, a fin seam and no extra fins,
which makes them not the best of swimmers, but perfectly adapted to a
life predominately in cracks and crevices of rocky and coral
reefs.
Japanese and Hawaiian Dragon eels
Enchelycore pardalis occurs in many parts
of the tropical Indo-Pacific. The species can be found from the West of
the Indian Ocean around the island of Réunion to Hawaii in the East
and from Southern Japan and South Korea down to Line, Society and New
Caledonia in the Southern Pacific. It appears to be quite rare in most
of these areas, maybe with the exception of Hawaii and rocky areas
between the Northern Philippines and southernmost Japan, where it lives
in subtropical to tropical waters. Specimens are hardly imported from
other areas. Therefore, the common names 'Japanese Dragon eel'
and 'Hawaiian Dragon eel' are used in trade to indicate where
specific eels come from. This has also led to the misconception that
there are two different species. All Japanese and Hawaiian dragon eels
at the current state of knowledge belong to one species: Enchelycore
pardalis. Potential differences in coloration of specimens
from the two different regions are not well reproducible. You can find
both pale and colorful individuals around Hawaii and South of Japan.
The amount of red, orange, black and white as well as the size of the
white spots can also differ with age, possibly even the habitat (this
is known for another morays such as Gymnothorax favagineus,
Gymnothorax pictus). If you expect a definite answer on how to
differentiate between Hawaiian and Japanese specimens, you probably
will be disappointed. Feel free to compare diver pictures with given
locations (e.g. flickr) as well as pictures from scientific literature
and fishbase yourself. However, be careful with pictures from the pet
fish trade. The Hawaiian dragon eel's species name
'pardalis' is a reference to the panther or leopard.
Especially outside of the aquarium trade you'll find the common
name 'Leopard moray' used in literature for this species.
However, this common name is also used for other species such as the
Tessellated moray (Gymnothorax favagineus) or Gymnothorax
polyuranodon, with the latter being the only one showing a
coloration very similar to the big cat.
Using the term 'Dragon moray' without
reference to a location can also easily lead to misunderstandings,
since several members of the genus Muraena, which possess
comparable hornlike rear nasal tubes have also been called 'Dragon
moray'. The common name 'Brazilian dragon eel' has been
used for Muraena pavonina, Muraena melanotis and
Muraena retifera (although the latter does not occur in Brazil).
Muraena melanotis is also called 'African dragon eel'
and Muraena lentiginosa is known as the 'Mexican dragon
eel'. Consequently the use of the scientific name
Enchelycore pardalis in general is most helpful, but in this
specific case 'Japanese Dragon eel' and 'Hawaiian Dragon
eel' are also pretty much unambiguous. A lot of older literature puts this species into
the genus Muraena (making the complete name Muraena
pardalis) and indeed it does have a few characters in common with
Muraena species, especially the hornlike elongated rear nasal
tubes mentioned above and the skin structure on top of the head. The
elongated rear nasal tubes are not present on other Enchelycore
species. What makes the Hawaiian dragon eel superficially similar to
other Enchelycore spp. are its slender and curved jaws that
cannot completely close and the very long teeth. Two other synonyms of
this species are Muraena kailuae and Muraena lampra. Males and females
One topic you'll eventually stumble over when
researching Hawaiian dragon eels is how to sex these eels. There is
quite a number of people claiming to be able to do that given various
morphological or chromatic features (e.g. 'males have more orange
on head and neck and a more stippled pattern on the body', see in
Michael, 1998), some saying they just know it without being able to
formulate more specific guidelines. Most interestingly all these claims to
my knowledge have never been substantiated by production of fertilized
eggs or alternatively dissection and examination of perished animals,
leaving it unknown until now if members of this species can be sexed
and which ones are the females and which ones are the males. The fact
that quite a number of moray species can change their gender or
apparently occur as simultaneous hermaphrodites makes the usability of
genetic methods and even the evaluation of possible, fertilized eggs
pretty much doubtful. It can be concluded that so far no method is known
to me to sex this specific moray eel species, while some other species
can be sexed by their dentition e.g. Snowflake morays (Echidna
nebulosa), Barred morays (Echidna polyzona) and
Gymnothorax richardsonii or at least in nature apparently by
colour (Rhinomuraena quaesita). However, if you want to sell a 1.000 $ fish or
enjoy showing it off pulling some mystic information about the gender
out of your hat is certainly more impressive than admitting 'I
don't know' or saying 'Based on '� I have an
assumption, but'�'. Consequently, just like other morays, they
have not been reproduced in captivity. Life in natureSimilar to most morays this species leads a
nocturnal and secretive life and likely most specimens, especially
smaller and therefore more vulnerable ones, are not seen by divers at
all. Michael (1998) noted that this species is often found in
Porites compressa corals. Sometimes two Hawaiian dragon eels can
be found sharing the same hideout, rarely they are seen with other eels
nearby such as Gymnothorax kidako in the Southern Japan
area. The few cases where stomach contents
have been examined indicate that this eel mostly consumes other fishes.
Very likely Crustaceans and Cephalopods (especially octopuses) are also
eaten.
Captive care
Enchelycore pardalis reaches a length of
about 3 feet (92 cm) and at this length has a greater girth than many
other moray eels. They become easily as thick as a male lower arm with
age. I'd consider a 125 gallon tank as the
reasonable bare minimum for a single specimen. For long term care both
the keeper and the fish would probably be more happy with a tank larger
than 200 gallons. Especially, if you want to keep this eel with various
corals or other compatible invertebrates the dilution and filtration of
the larger system will be very beneficial. For a second eel, add at
least 50% of tank size (preferably 100%). Other useful things to know when keeping Hawaiian
dragon eels are: - Keep the tank closed (lid, net, very high frames
have worked for at least some). Otherwise, the curious eel may decide
to explore the outside of its new home. - They do well at standard marine aquarium
temperatures (76-80 F, 24-27°C), but can also be kept up to 2-3°C
colder if the other organisms in the respective tank also live at these
temperatures. - Provide enough caves: You can use simple live
rock constructions, but my advice is fix them either with appropriate
glue or concrete, or at least with cable wraps. A non fixed composition
will be destroyed at some point by an eel of this size and you will
have rocks tumbling around in your (likely glass) tank. In extreme
cases and heavy rocks even the eel might get hurt. Personally I
incorporate PVC pipes in all tanks for medium sized to larger moray
eels. Offer at least 2 or 3 caves per eel. - Feed a varied diet. Use mostly fillet of a
variation of marine fishes. If you have them available you can also
feed heads and tails as well. Additions are shrimps and other
crustaceans as well as octopus, squid and calamari. If you feed mostly
frozen food, add vitamins about one time per week to avoid vitamin
deficiency diseases. Younger Dragon eels can be fed 3 times a week, for
larger ones 1 meal per week can be sufficient. A meal should be about
as large as the entire head of the eel. If you prefer daily feedings,
decrease the size of the ration accordingly. - Provide enough oxygen. A strong skimmer and
surface movement with stream or powerhead pumps will help with the
gaseous exchange of tank water and air. - Keep the water clean. PH should be between about
8.0 and 8.4, nitrates below 20-25 ppm and nitrites and ammonia should
never occur in measurable concentrations (hobby test kits that
is). *Suggested position of pictures 5 and
10*
Compatibility
I recommend a specimen tank. There have been
numerous attempts to keep these eels with other fishes by various
keepers. While this works sometimes for months or even years especially
with groupers or other stout tank mates, most fishes, which can be
eaten are eaten at some point. Even fishes too large to be eaten, can
be bitten badly. Some had limited success with very small and fast
fishes that in general are not worth the trouble of hunting them for
the moray such as Chromis, but you may see them vanishing one by
one. Basically Hawaiian dragon eels can be kept with
other moray eels of the same or preferably slightly larger size in
sufficient tanks with enough caves, but there are also cases where this
has gone wrong. It depends mostly on the individuals you put together
and prognosis can hardly be given. Lysmata Cleaner shrimps, even
Stenopus spp. can work, especially if they have been added
before the eel, but after all there's no guarantee they won't
be eaten. If they are not, however, a Dragon eel cleaned by a bunch of
cleaners is an interesting sight for sure. Diseases
Enchelycore pardalis can reach ages of more
than 17, probably more than 20 years. Given a proper environment (clean
water, little stress) and a varied diet, these hardy animals rarely get
sick. They are almost never affected by protozoan diseases such as
Whitespot ('Ich', Cryptocaryon) or Velvet
(Amyloodinium), but can be infected by bacterial diseases,
especially in a not-so-prefect environment or with a weak immune
system. This is best prevented by an adequate environment and proper
diet as noted above. Sometimes dragon eels will stop feeding. This can
be related to stress (moving, inadequate tank mates), bad water quality
or simply overfeeding in the months before. A healthy eel can go
without food for a few months and as long as the water quality is fine
and no further symptoms occur a fasting Dragon eel is no reason for
concern. Résumé
Dragon eels can be very interesting animals to
keep, they command a high price and need a well planned and filtered
tank as well as a proper diet to lead a healthy life. Smile about some
of the myths spread in the hobby and enjoy them at home, in the zoo and
the ocean. Literature
Lichtenberger, M. (2008): Muränen im
Meerwasseraquarium (moray eels in the marine aquarium).- 64 p., Natur
und Tier Verlag, Münster (in German). Michael, S.W. (1998): Reef fishes vol. 1.- 624 p.,
TFH Publications. Purser, P. (2005): Moray Eels in the Aquarium.- TFH Publications. Randall, J.E. (2005): Reef and shore fishes of the
South Pacific: New Caledonia to Tahiti and the Pitcairn Islands.
University of Hawai'i Press. 707 p. Randall, J.E. (2007): Reef and shore fishes of the
Hawaiian Islands. University of Hawai'i Press. 546 p.
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