Cephalosilurus apurensis
- a voracious ambushing predator but not without charm |
Christopher
and Wolfgang Ros
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nformation to care and behaviour of
species of the genus Cephalosilurus up to today
are rather scarce, but perhaps it is just this "breath
of mystery", which stimulates one or another aquarium
enthusiast, because finally we can get these unusual animals
and study some fascinating observations.
The genus Cephalosilurus was described with four
species so far. To that extent it surprises me that even
in relevant internet forums confusion still prevails. It
concerns the species identification from specimens of this
genus belonging to the family of the Pseudopimelodidae,
which are introduced to the forum members by means of photos.
The first part of its name originates from the Greek as
the the genus name underlines very clearly, with what animals
we have here: "Cephalos" stands for head, and
its broad shape captivated by its massive front body half
and particularly by its uncommonly large head, which looks
more enormous because of the small eyes, and the not less
enormous broad head muzzle. Therefore however it has authorization
already, to state the species belongs to this genus in English
language predatory fish forums as prime examples of the
way specified monstercatfish may be undecided. A short overview
of the genus follows to describe our own experiences and
the determination and care of some specimens.
Amongst the two largest of the four described Cephalosilurus
species are C. fowleri resident in Brazil and C.
apurensis from Venezuela, followed by C. nigricaudus
from Surinam and the smallest species C. albomarginatus
from Guyana. Above all the larger species they prefer rivers
with a rocky soil which is associated with plenty of good
hiding places. There they mainly pursue fish motionless,
as in the best way camouflaged hunters do. Refraining from
C. albomarginatus, which were probably not introduced
for keeping in aquariums, the other species are imported
occasionally at least to Germany. In the trade there they
cost, depending upon size, and (not always correctly) sales
designation, between 60 and 200 euro, in most cases it is
C. apurensis that is sold.
Identifying Species:
Because our locally zoo specialist dealer on our request
had seen none of the species belonging to the genus Cephalosilurus
and made us of little hope of being able to procure them.
We looked up the on-line stock lists of specialized catfish
dealers and there we discovered them and was sent two C.
apurensis. When unpacking the polystyrene crate we
had to determine that due to an unexpected cooling down,
despite heat packs and other precautions, the temperature
in the two water bags were down to 18 degrees Celsius, the
bags were sagging and the animals did not move any longer,
but were obviously not yet dead. After slow adapting of
the temperature they were set into separate tanks. In each
case we had prepared these before - their natural habitat
accordingly - particularly with large rounded stones, in
addition with pieces of wood and a cave as a possible hiding
place.
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Our first specimen of C. apurensis
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Both recovered rapidly from the strains
of transport. They were brownish with grey-black, exhibiting
partly arranged markings. A colouring in this young age
is typical for C. apurensis. Also their strong
body with the large rounded tail fin spoke for this species.
What made us somewhat perplexed was this quite dark colouring
of the tail fin which referred rather to C. nigricaudus
(the Latin name means „black tail"). Thus we
sent photos of the animals to the Brazilian ichthyologist
Dr. Oscar Shibatta (Londrina) who is scientifically involved
with the Pseudopimelodidae family and addressed him particularly
on this coloured likeness. He described in his answer that
all kinds of the genus Cephalosilurus, at least
in youngsters, have dark tail fins. So from this alone no
conclusion could yet be ascertained on a certain species.
Since it concerned our own specimens with twelve and 16
centimetre young animals, their identification remained
further unclear, particularly since photos, which show with
sufficient clarity the species C. nigricaudus which
are suitable for comparison purposes, have scarcity value.
And with scientifically still unconfirmed theories of keepers,
according to which for example the same length of the upper
(mandibular) and lower outside barbels (maxillary), is to
speak for C. nigricaudus, and if these are longer,
it points to C. apurensis. We would not like to
occupy the reader with more intensity.
The fact seems to be that C. nigricaudus is actually
more darkly coloured than C. apurensis. The demarcation
of the species becomes extremely difficult, and according
to the statement of Dr. Shibatta not only the knowledge
is necessary around the exact discovery location for identification,
free of doubts, but also counting the gill rakers (it concerns
bony or gristly extensions of the gill arch). Their number
varies with C. apurensis, around 27, and lies with
C. nigricaudus between 11 and 16. However we wanted
to save this procedure to our animals, anyway it can probably
only be used with dead specimens.
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Our second specimen of C. apurensis
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According to the statement of the
dealer with whom we had taken up contact again, our catfish
originated from a Colombian import, however they were definitely
caught in the Rio Apure in Venezuela. Therefore it must
represent, to its discovery place, which is the Apure River,
the species C. apurensis. Later we ourselves had
further dealer send us a third specimen of the genus Cephalosilurus,
which was offered as C. fowleri. The price made
us a bit perplexed because this species was always sold
more expensively. Indeed it was approximately already 20
centimetres long and the specimen differed in terms of colour
from the two other animals, however it was clearly not C.
fowleri as it would have been typical, but rather still
more darker. Its shape also was not noticeably flatter -
as characteristic of this species -; see André Werner
(2005): „New imported: Cephalosilurus fowleri"
together with photo in: Die
Aquarien- und Terrarienzeitschrift“ (Datz) 58 (11):
29.
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Our third, not clearly classified catfish of the
genus Cephalosilurus
(Ed: Update as of Jan.2008. Now classified
as Cephalosilurus nigricaudus and can be
found in the Photo Gallery
here) |
Does it possibly concern an undescribed species of the genus
so far?. For the thesis, except the four mentioned it could
give a number of further not described species, so at least
some specimens illustrated in predatory fish forums, which
due to remarkable differences can not be determined to the
one or the other, until now described species. Nevertheless
most of them might have to be added as C. apurensis
in the long run because there are obviously different variants
of this species which look different in colour and patterning
depending upon origin. On request the second dealer communicated
that the sent specimen originated from Venezuela, the exact
discovery location was not known. With this exclusive information
the knowledge of C. fowleri occurring in Brazil
separated them. Perhaps with our third specimen it could
be C. nigricaudus, however its circulation area
would be then more largely and not exclusively limited to
Surinam, or may be a variant of C. apurensis. After
given photos to Dr. Shibatta he explained that the identification
problem here could be finally clarified only by a scientific
investigation of the animal (including counting of its gill
rakers). This with increasing size it became more darker
and exhibits also otherwise little differences in the body
form, even in the behaviour. So compared with the two other
animals it altogether does not only seem to be somewhat
more aggressive and more attack minded, but it is also far
more greedy, in addition only this specimen in its hiding
place seems to give off every now and then a kind of secretion
(probably primarily over its muzzle).
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The secretion on a
stone from the third specimen
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Keeping in the aquarium:
The species C. apurensis, C. fowleri and
C. nigricaudus imported every now and then will
indeed grow large, but however there is a crucial advantage
in keeping them. Due to their expressed location their urge
to move is only very weakly pronounced and compared with
some other large predator catfish of same origin they are
also not very good at persistent swimming. Even if they
(however only in exceptional cases such as escape or catching
prey) are able to move abruptly, then they prove altogether,
exactly like their clumsy shape, as rather slow acting.
Our animals actually only move if they expect food then
they come out from their hiding places. Therefore one needs
aquariums with large surface area, much free swimming area
however is not a necessity. Even with lengths of over a
half meter they are still well accommodated in two meter
tanks. Important however is a sufficient depth, on the one
hand it should amount to at least 70 centimetres only then
can it be ensured that the adult animals can create adequate
hiding places. On the other hand one, should aim for large
individuals, at least a tank height of 65 to 70 centimetres,
what is connected with it in the long run is its attainable
length and its "favourite position", with which
we will deal with later on. With this keeping it will surely
accommodate the quite short barbles of these species. So
one will have to offer them the comparable final size. Long
barbled and more active predatory species like Perrunichthys
perruno or Leiarius pictus prefer far roomier
tanks, in order to guarantee that their barbles don't touch
the tank sides when manouvering, thus the animals are then
placed in a stress situation.
So that the photo sensitive catfish feel well, the aquarium
should be only moderately lit up during the day. A floating
plant cover, which provides parts of darker zones, offers
itself likewise. During the recommended weak lighting many
plant types are not applicable. Beside undemanding floating
plants other plants such as Vesicularia dubyana
and Microsorum pteropus are suitable. Otherwise
one can use if necessary still frugal Cryptocoryne
or Anubias species, however these can be easily
disrooted by the strong animals. As ground soil of a mixture
from gravels of different granulation is recommended. The
creation of a possibility for hiding is particularly important.
Cave hiding places of any kind are gladely taken. These
are necessary at least for the well being of juvenile animals.
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C. apurensis needs hiding places for its
well being, from which best it only lets the head
stand out like here
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For larger specimens a roomy, firm
shelter is recommended, at least it should give possible
retreat under or behind roots, wood or between large stones.
The catfish will gladly dig hollows and so create themselves
their own hiding places. In no cases should the keeper create
a hideout by loose stacking up of heavy stones! Even if
the animals accept this gladly, there increasing strength
will make it possible one day to bring the structure of
stones crashing down with all negative consequences.
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This animal has taken its hiding place between large
stones
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Obviously C. apurensis is
very durable, because diseases never arose with our animals.
And even the concern of keeping them being more difficult,
because they originate from running waters, is unfounded
due to its amazing adaptability, nevertheless one should
provide an easy current . Recommend is also the employment
of a high performance filter/cleaner, and as with all large
fish weekly partial water changes are an obligation. The
water equivalents are of subordinated importance. The temperature
should lie between 22 and 26 degrees, however the animals
can stand higher temperatures temporarily.
Nutrition:
Feeding our animals is unproblematic. At first C. apurensis
in the aquarium eat only living fish, however our specimens
were accustomed already obviously to other foods. From the
beginning they could be lured from their hiding places with
shrimps, worms, thawed out smelt, in addition with pieces
of fillet of fish. Even FD food tablets were taken, however
these should be handed only to smaller specimens, for larger
such servings are much too small. Sporadically we feed our
animals almost exclusively with pieces of thawed out tilapia
fillet and trout. Obviously pieces of trout with bones and
other components contain everything that is important for
their digesting, but also its growth, and in addition for
its well being. Naturally predatory catfish gladly take
living fish, with C. apurensis giving live food
however is unnecessary.
During feeding basically one cannot do anything wrong by
giving it too much and also not too often since these catfish
are never completely full. So as long as the already acclimatized
specimens do not even make to visit the feeding place it
should not then get food, otherwise they threaten to easily
get fat. Their large and very flexible stomach is appropriate
and adequate to digest giant portions but then can go for
days or for weeks when no food is available. In addition
another weighty criterion arises. The animals do not move
frequently and then since they do not burn much energy,
they do not have a fast metabolism and already for this
reason do not require of daily food intake. Two to three
feedings per week worked satisfactorily with our specimen.
Basically even a larger meal in the week would be completely
sufficient without the animals having to starve.
Aquarium observations:
A condition for an interesting view of the life of these
animals is that the keeper places the necessary hiding place
in such a way that it can be well seen by him, then he will
soon see that his C. apurensis, which already holds
a third of its body rising up out of the hiding place, is
well looked after. In addition the keeper can observe the
animal, after it snatches its food morsel outside of the
hiding place. Because the catfish custom is to devour and
digest this completely, particularly as a young animal,
only after its return to its dwelling. Thereby it turns
regularly, rolls a few times on the side, every now and
then, even on its back. Several times it briefly tears also
the muzzle up and seems to harness the body altogether.
These are movements, which probably advance digesting with
even larger food morsels.
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For digesting purposes C. apurensis tears
the muzzle wide open
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In order not to have to give up its
hiding place, C. apurensis with its progressive
body size, undertakes all efforts to extend this and adapt
to its respective body form. If the animal takes its usual
quiescent place for example under a wood root, then one
is able to observe soon how it moves parts of its body back
and forth on the soil, in particular head and belly, in
order to widen its place in such a way as to develop the
recess.
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With getting bigger C. apurensis must be
offered roomier hiding places (like here a large
amphora)
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The second opening of the same dwelling is gladly
used in this way for observation purposes
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C. apurensis
releases enormous forces with these excavation activities
and here particularly can move even larger stones by means
of its tail fin. The aquarium trade can offer artificial
caves only to serve young animals as hiding places. Already
for specimens of more than 30 centimetres body length, commercial
cave sizes might be limited and usually too small. From
then on we took accordingly large hiding place possibilities
such as roots and/or large wood-pieces which are visually
good looking. One can help also with largely dimensioned
hiding places like to some extent optically pleasing, amphora
(A two-handled jar with a narrow neck used by the ancient
Greeks and Romans to carry wine or oil) from the horticulture
shops, whose openings were if necessary additionally extended.
As soon as C. apurensis accepts a new hiding place,
it defends this exactly the same as any other species.
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Unrestrained strength: Over night the animal turned
the heavy amphora over
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With the onset of darkness C.
apurensis usually comes out from its shelter and moves
sedately one or two turns around the tank, before it returns
back into its hiding place. Interestingly enough all our
specimens at night have alternative staying places in the
proximity of the outlets of the filters, on which they rest
over some hours. Probably the animals visit places of different
flow at this time, also in nature, depending on the locally
of available feeder fish. With their "tours" if
obstacles stand in their way such as wood pieces, they try
sometimes, despite their thick bellies, to go directly through
them. If that does not succeed, they react with an expressive
change of mind. They become "enraged" and they
seem to rear up formally against the barricade, and with
opened mouths they try to completely force this away. The
unrestrained strength used can not be underestimated by
the keeper. Above all, larger specimens in this situation
show less tolerance in relation to the aquarium mechanism/outfit.
Then it can happen that they abruptly try to force away
any objects and among these, heavy wood and also large stones,
but that is still the harmless variant. Because the enormous
mouth in such a situation is able to destroy technical devices,
thus the aquarist, who fastened the heater for example directly
to the side glass! Accessories such as heaters and pumps
may not be unprotected in the tank with these strong and
sometimes somewhat self willed animals! They can show this
described behaviour also when they are long overdue a feeding.
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This hungry specimen is already reacting a bit angry
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All species of the genus Cephalosilurus first of
all are pure lurking predators, which make rich prey above
all of other fish on their annual migrations through their
area. Also in the aquarium they await in front of their
cave or between large stones and woods motionless on the
fact that fish of suitable size will approach near enough.
With the camouflage however they themselves go not as far
as the South American more specialized lurking predator,
Lophiosilurus alexandri, which entrenches itself
nearly totally in the sand. With the hunt at which the animals
can partly also gradually stalk its victim, only a subordinated
function comes to the optical sense, mainly these are the
barbles which signal to the catfish, released by lightly
water movements. When it is promising success it break its
enormous muzzle, thereby a negative pressure develops which
sucks in the victim formally. Once snapped it is held tight
definitely with the help of the strong jaw and a multiplicity
of smaller rows of arranged pointed teeth. Then the cat
fish moves itself partly backward into its hiding place,
the prey not yet completely devoured. To large prey fish
C. apurensis above all will dare if "suitable"
feeder fish are not available, even after a long involuntary
fasting time, to which however C. apurensis can
quite attune itself. Then it snaps approximately fish equal
in size and devours it gradually with the head in front.
Thereby the muzzle can be stretched much. However on such
a meal the catfish can live a long time.
Relationship to the keeper:
C. apurensis is a little shy as a youngster and
also in the phase of acclimatizing, afterwards the confidence,
particularly of larger animals, is impressive. They are
teachable, can be tamed and also accustomed to a firm feeding
rhythm. Our specimens meanwhile swim to the front glass
as soon as we approach the aquariums. At the usual feeding
time they appear also when the lights are switched on. Although
otherwise predominantly bottom dwelling fish, C. apurensis
does not shrink from rising up into the upper third of the
water table. In a vertical position, with the head upward,
he stands before the food is given. Thereby one can hardly
elude from its outgoing charm.
As soon as the food touches the water surface, C. apurensis
tears it up with its mouth in addition to being so gluttonous,
if we immerse the disk magnet in order to clean the tank
panes of algae this causes the animals to bite heartily
into our fingers so that it would be better to refrain from
their designation as "tame to the hand". In such
an inadvertent practice test however it can be reconstructed
very close to that shortly after actually snatching immediately
a second time, stronger and biting, escaping hardly is possible
even for large prey fish. For the keeper such a gripping
is not dramatic, if it concerns adolescent individuals,
bites of larger animals however are pretty painful and can
lead to bloody skin scratches for the consequences.
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The animals are not always
so tame as it seems to be here with feeding
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Against this background it may surprise
that we touch and even pet one of our specimens with the
hand. Its body feels exquisitely soft probably due to the
high fat content. Unfortunately it does not send peaceful
signals in time, as soon as it is weary of the "tender
loving care” it rather abruptly tries to snatch at
the hand, one must be already rather fast, in order to be
able to with draw the fingers in time.
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C. apurensis permits contacts after habituation
and enjoys it obviously, but caution is required
here also
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Growth and final size:
Every now and then is to be read that C. apurensis
is a species compared with other predator catfish growing
rather slowly. We cannot confirm that. In the first, at
the same time strongest growth phase our specimen, in
only three months, carried out jumps of 12, 16, 18, 25,
20 to 28 centimetres. Starting from a length of 30 centimetres
growth slows down somewhat. The 40 centimetre mark is
reached after a further ten to twelve months. Our largest
animal exceeded meanwhile the overall length of 45 centimetres.
From this size C. apurensis adds more to the
girth than in the length but even now the growth length
is not yet final. So is to be assumed when good feeding
the animals can grow up in the aquarium, to reaching the
first life decade slowly, but constant, up to approximately
65 centimetres of length. According to Japanese sources
even lengths of 70 centimetres and over it are possible.
With the growth of the animals also their colour pattern
changes. The youth dress of C. apurensis loses
something at contrast, the brown yields a rather base
ochre-pattern. Therefore apart from the characterisation
as "jelly catfish" comes the not completely
applicable designation of "orange catfish”,
which is common likewise for C. fowleri and fits
this rather because of the orange base colour of C.
fowleri. In the adult stage the animals are even
more sedate, however they emit a rather uncommon peace
and dispassionateness, as if they would almost know that
hardly anything can harm them.
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Typical youth colouring of C. apurensis
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Optimally to the environment (stones and wood) the
adapted colouring of an older specimen
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By the way for the keeper of C.
apurensis it is made very easy to measure his animals
and so to be able to make secured statements about growth.
That is connected with their described "begging position",
which they take punctually at the stated feeding time within
the area of the tank sides.
Rapid movements, which could affect the result of measurement
and which could bring some aquarists to the edge of despair,
if they put the measuring tape at their fish, do not to
fear with this species. In all peace of mind the animals
will remain at least for a long time in their vertical position
and will accept measuring until feeding was made.
----Begging position at the
usual feeding time---
Socialisation:
Generally the genus Cephalosilurus is considered
as very territorial, this particularly applies to the
intra species aggressiveness. C. apurensis does
not defend acrimoniously its own quiescent place, but
also the surrounding district. Weaker species comrades
are tormented, so for a long time until they perish due
to bite injuries and the continuing stress situation.
Even in very large aquariums therefore the socialization
with species comrades, in addition with other Cephalosilurus
species is not possible.
At first, when the moving was possible without larger
circumstances, we united our animals several times in
different constellations for short times. The result was
always the same, either the added specimen straightway
moved to the cave in which the other one was, by the way
it showed this purposefulness also during supply of several
hiding places, or however the "long time-resident"
attacked the new species comrade immediately. Probably
the animals deliver substances which due to their strongly
pronounced sense of smell make a goal exact detection
for them possible. Directly before meeting the two fish
took a threatening position. Thereby in each case the
smaller specimen usually could not be impressed by its
larger species comrade, so that meetings with one another
was inevitable. With their bodies pressed together both
animals measured their powers in horizontal attitude,
with muzzles opened far and by trying to force itself
away mutually. Additionally the tail fins were struck
against each other. These fights looked threatening, however
were only for a short duration, because usually one of
the rivals would take flight whereupon we separated the
fish again.
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Internal species aggressiveness: Two young C.
apurensis with the fight for a hiding place
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Indeed C. apurensis behaves
as a young animal, up to a length of 20 to 30 centimetres,
with co-inhabitants rather peacefully, but already then
all fish, which are not larger, live constantly in the danger
to be eaten. If one would like to keep this species with
other catfish, then put non predatory beside them, those
like the Loricariidae are applicable above all predatory
catfish of South America, however they should not be too
territorial for their part and at least equal in size, because
as soon as C. apurensis takes offence, or if the
other fish want to make its hiding place disputable, it
proves itself as quite assertive. In the context of such
an argument it positions itself first before the aggressor,
confident on the fact that this alone can turn them away
at the sight of its massive shape. If that does not help,
C. apurensis snatches at him abruptly. Thus C.
apurensis then terrifies the opponent so much that
in future meetings the opponent always pulls back. Also
different large, durable cichlids can be kept together with
C. apurensis and soon as these come into the direct
proximity of its favourite place, it snatches at them to
make clear the requirement for possession. They soon realise
however they have noted the quite small radius, which they
may not cross, in order to release its attacks. If one falls
back to cichlids, then a weak night lighting system is of
advantage. With one tank we decided in this regard for moon
light lighting, it ensures that the catfish does not disturb
its co-inhabitants too much at night, in this case, two
adolescent Astronotus ocellatus. If the lighting
is completely switched off, then the danger is largest that
even with only moderate appetite, co-inhabitants due to
contact by the catfish, scurry away frightened in the aquarium
and thus only the hunt instinct is wakened by C. apurensis.
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"Eye to eye“:
Generally C. apurensis gets along with
its associated cichlids only if they are large enough
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"Sic semper tyrannis“: Even getting nudged
by the astronotus the catfish is going
to attack by oneself with increasing growth
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In principle it applies with a considered
socialization to respect the habituation effects. If a C.
apurensis was already fed over a long time with living
fish, then other species can hardly be kept together with
it, otherwise the socialization functions after our early
experiences, if socialized fish grew up together with the
catfish; then they are regarded probably less as victims
and rather as co-inhabitants. Actually a Petenia splendida
female of not even 20 centimetres of length has been kept
since the beginning in one of the apurensis tanks
without have been ever troubled by the catfish. However
a Crenicichla sp. at 25 centimetres, from which
a friendly aquarist had to separate owing to circumstances
and which we put to one of our apurensis, couldn't
survive on the first night. On the next morning one saw
the tail fin, which looked out from the mouth of the predator
while the front part was already digested. The animal nearly
motionless awaiting in its hiding place breathed very heavily,
its whole abdomen seemed nearly to burst, so strongly it
had swollen, and that was a further day after the prey was
completely eaten. Here it does not only show up how strongly
new acquisitions are endangered, but that C. apurensis
posesses the ability to be able to attack and to devour
even fish and other predator catfish of comparable size.
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This co-inhabitant (Heros efasciatus spec.
"Rotkeil“) remains undisturbed even in
the dwelling place of C. apurensis
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In another case, the victim, a nearly
25 centimetres long A. astronotus, which was given
in addition to the two mentioned above somewhat smaller
species comrades, yet had luck. Already a few hours after
putting it in the tank we saw it in the mouth of the only
about 15 centimetres larger catfish. Even strong knocking
at the glass sides did not impress the apurensis
in the slightest. Only when it was gripped at the head with
the hand did it release its victim again. Thereupon the
astronotus immediately dashed to another part of
the tank. Indeed clearly branded by the bite, he survived
the attack as by a miracle, even only one week later the
bite wound could hardly be seen. We of course immediately
removed the astronotus to another tank.
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Two snapshots: The catfish snapped up the astronotus
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The victim: One day after
the attack and then only one week later (the healing
process is already clearly advanced)
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To some extent the socialization with
fresh water Potamotrygon of comparable size such
as Potamotrygon leopoldi can function, however
it requires completely different tank lengths than those
which were mentioned before for the single keeping of the
catfish. One of our animals is associated with a P.
hystrix male. The past experiences speak for the fact
that a peaceful coexistence is possible here. On the other
hand the aggressiveness of C. apurensis is to increase
with age. Since Potamotrygon can defend themselves
if necessary with their poison pricks, a separate keeping
of them would be indispensable and culminating as soon as
it can be found out.
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Socialization (here with Potamotrygon hystrix)
is only possibly reduced
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Once it came after feeding, in the
dwelling of C. apurensis associated with the Potamotrygon
hystrix a fight with nearly fatal consequences and
a fraught exit. Into the apurensis amphora
hiding place came the Potamotrygon for the
first time it had dared, attracted by the food remains,
whereupon the catfish snatched immediately at him. Thereupon
the Potamotrygon was running scared and had not
found the exit at once and probably therefore under threat
defended himself. It hit the apurensis within the
range of the tail fin, fortunately it survived the sting.
For approximately one month it lived completely withdrawn
and took no more food to itself. After a further three weeks
however nothing more was to be seen of the wound and the
animal behaved again completely normally. This could permit
the conclusion that C. apurensis is at least partly
immune to the Potamotrygon poison partly because
the prick hit the catfish in a comparatively rather insensitive
place and in addition obviously not completely. Thereupon
as a precaution we have replaced the amphora by a large
clay container with additionally extended openings by which
the Potamotrygon in doubt can swim free without
any problem. Since then there has been no recent incidents.
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Spine of Potamotrygon hystrix
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C. apurensis with the sting injury by this
spine
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If you have an extremely large tank,
a socialization could be considered for example with "Giant
Characidae" as to the red Pacu (Piaractus brachypomus),
since the prognosis even on a long-term basis seems favourable
here. However with C. apurensis the single keeping
remains general and always the safest variant.
Sex differences:
Over the sex differences of the Cephalosilurus
species there are no secured information. With our animals
it concerns, if one puts at the basis the oblong and course
sharpened form of the genital papilla, obviously over the
same sex and with it males. Some speak for the fact that,
as with Lophiosilurus alexandri, adult females
are larger and in the first body third more broad and more
brawny than males. Additionally, at least with C. apurensis,
one reports the differences in the behaviour. The female
animal shows itself as the more aggressive. For the reproduction
of the Cephalosilurus species there is no knowledge,
in tanks they have not been bred so far. Since the catfish
lives solitary, the male and the larger and stronger female
can only in a determined time interval, be tolerated for
the purpose of the mating in its area.
Result:
Whoever has kept the already smaller predatory catfish will
also be inspired by these large predators. Anyhow we are
fascinated by the animals. With increasing length they,
particularly by their increased confidence, are constantly
more an attraction.
Even if these catfish in our opinion
are suitable, of the large predators, for home aquariums,
their care remains something for experienced specialists.
It must be clear that a socialisation is only conditionally
possible in very large tanks. For most aquarists however,
even the absolute "Catfish freaks" among them,
in the long term it might be too monotonous to fill their
tank with a single giant.
Note: This article is published in May
2007 in the German publication: Die
Aquarien- und Terrarienzeitschrift“ (Datz) 60 (5):
38-42.
Our thanks apply here for the Datz
editorship and her editor-in-chief Rainer Stawikowski, who
gave us kind permission for placing of the article on ScotCat.
Owing also to Dr. Shibatta for the given details. In some
places the text was supplemented and in addition further
photos were added.
(C) Copyright in text and photos: Datz
http://www.catfish-and-more.com
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