mong the representatives of this genus,
Cephalosilurus fowleri is regarded as having the worst
reputation. The information which pertains to this species so
far can be summarized in this way: Grows very big, extremely
aggressive, voracious and is also a very expensive acquisition,
but is this view well founded?
species have been described to the genus Cephalosilurus
resident in South America. Three of them have been introduced
for keeping in the aquarium, C. apurensis, C. nigricaudus
and C. fowleri. From their form they are only little
differences from each other.
Their trademark is the big head with
the little eyes and short barbles but with an almost head wide
mouth. They are sluggish animals which hardly move and only
lie waiting for prey. C. fowleri is to be found exclusively
in the Rio São Francisco of Brazil and there mainly in
the more calm flowing river sections.
C. fowleri, 35 cm in
length with its typically rubiginous colouring (© W. Ros).
This species is regarded to be relatively rare, so in this respect
its identification at times can be difficult. Some years ago
the few captured specimens almost always without exception have
been transferred to Japan whose residents have a great enthusiasm
with big catfish and accept them at almost any price. The USA
and Europe markets with imports were usually excluded, lately
however there has been imports into Germany. One would be bound
to sight the on-line stock lists of specialized dealers to acquire
such a catfish, but some caution is required with the purchase,
because sometimes the cheaper C. apurensis and C
nigricaudus are offered "for 100 per cent" the"true
Fowleri". Since it is here in the elevated price range,
every respectable dealer will understand if the interested party
asks for the sending of a photo of the offered specimen before
the purchase. If it should actually be the "true Fowleri"
and the price is correct, it is necessary to be quick with the
purchase as sometimes one to two years can pass until the import
of the next specimen. Depending on the number of imported animals
the prices fluctuate strongly, in the past however it has dropped
considerably. In 2006/2007 a 15 centimetres large specimen only
costs between 100 and 200 euros in Germany; specimens at ten
centimetres could be bought for approximately 200 euros upward,
the costs for a potential delivery not included. The prices
have dropped further so that in April 2008 with a German dealer
who imports himself, one could purchase a 20 centimetres long
animal at a bargain price of at last 50 euros. Probably also
because each specimen occupied a tank on its own and therefore
could soon find buyers.
C. fowleri is the most attractive Cephalosilurus
species. As in the case of all representatives of this
genus there are also specimens of a bit different colouring.
These deviations alone can not be put down to the youth/adulthood
since even older animals can sometimes be different in colouring
In terms of colour these
three are attractive young specimens of 14 cm in length
Young specimens are more brightly coloured
and often almost orange. The juvenile colouration is primarily
because of the contrasts arising by two more or less clear dark
body stripes, a slight grain with black-brown spots and the
dark tail, anal, adipose and dorsal fins are very striking.
At about 20 centimetres these contrasts fade away increasingly
and the orange as a rule gives way to a rubiginous, up to deep
brown, with dark spots with the colour dress fitting better
on the natural surroundings. But even so animals with a yellowish
basic colouring are not rare. Aside from the colouring C.
fowleri is different from C. apurensis and C.
nigricaudus by its slimmer shape and its flat head. Moreover
it almost completely lacks the spots on the underside of the
Preconditions for keeping in the
In comparison with other predatory catfish which have long barbles
and are swimming constantly even bigger specimen of C. fowleri
don’t need much space. Tanks of about 600 litres are
possible respectively with more volume if one wants to keep the
catfish with other fish species. The depth of the aquarium should
be at least 60 to 70 centimetres. A fully-grown animal for his
well being should have natural or artificial hiding places to
be created, bog pine or a vessel of terracotta offers itself as
such a hideout. Keeping C. fowleri without such a retreat
only makes it look to the casual observer as if the catfish is
possibly in torture. Against their nature such animals can even,
on an open area, try to dig themselves into the ground. Like his
genus comrades C. fowleri is quite averse to light. To
make the acclimatisation easier for him, the aquarium should only
be moderately lit during the day or a floating plant cover should
provide darker zones in places. As aquarium gravel, a mixture
of gravel of finer granulation or sand is recommended. For the
rest this catfish is tough and can be kept well at a light current,
a temperature span of between 23 to 27° Celsius and otherwise
normal water parameters. It seems to be robust in principle when
it comes to diseases, however if his fins are damaged, as it can
happen with transportation or wrong keeping, due to biting with
species or genus comrades, then the cure phase lasts for a quite
considerable time, therefore one can see only seldom, really perfect
Shortly after placing in the tank the keeper will find out how
his C. fowleri will retire to the hiding-place created
for it. A Few days later the animal has waggled the bottom of
its accommodation free of gravel.
Already a medium-sized specimen can have
tremendous strength and is able to move, apparently without great
effort, even a heavy shelter by pressure with the head and moving
around with the tail fin to a place seeming more pleasant for
it. In this behaviour a similarity consists to the other Cephalosilurus
species which also live with pleasure in an accommodation and
"fit it out" according to their wishes.
If the previous hiding place has got too
small, then the keeper puts a bigger one in addition to the original
one. When C. fowleri has gratefully accepted it after
some nights, thereupon the earlier shelter can be removed.
View of C. fowleri sleeping
on its back in cave (© W. Ros).
The keeper does not need to worry if his
specimen needs much time for the acclimatisation, because C.
fowleri normally at first will almost at all times hides
itself and eats, for a Cephalosilurus species, only moderately
even if it enjoys itself in apparently good health. Not until
after some months does it get a little more active. While C.
apurensis, due to its greater appetite, already has at times
finds its way out from its hiding place even during the day, C.
fowleri however still lives predominantly in seclusion, often
laying on its back and taking an unusual resting position in its
shelter, however this catfish becomes wide awake if food is given.
It immediately comes out, snaps at the chunks which sink nearby
and quickly retires again. As in the case of all Cephalosilurus
species the keeper can observe in that C. fowleri helps
its digestion of larger food pieces by regular turns of its body,
by rubbing of the epigastrium (the region lying on or over the
stomach, just below the sternum) at the feeding place, and by
tearing its mouth wide open.
If the acclimatisation process is completed, C. fowleri
at the latest, at nightfall, moves around through the tank before
it returns into its accommodation. Besides that the animal can
be seen as soon as it is hungry, then particularly fully-grown
specimens can sometimes lean, the head held high, against the
side glass of the tank.
But after feeding they also love to rest
in their hiding-places and to digest the food there, also then
if it is only behind a big root.
Like its genus comrades C.
fowleri, after swallowing larger chunks, tears its mouth
wide open a few times (© W. Ros).
C. fowleri makes its swimming movements more jerkily
and faster than its plump, far more portly appearing genus comrades.
Its agility is of benefit to it also at hunting time.
So C. fowleri is not only reliant
like the other Cephalosilurus species on waiting motionlessly
and disguised very well that fish of corresponding size fall below
the attack circle, which seems to be worthwhile for a sudden bite.
In a moment this specimen will
leave its hiding place to stalk (© W. Ros).
In fact as an active hunter in addition it can search the ground
between stones and woods with, from time to time, astonishingly
quick movements and when tracking down scared prey it can push
forward like a torpedo as quick as a flash. As soon as the prey
is grasped once with the gigantic mouth, it is hold firmly tight
with the help of the strong jaw and a multiplicity of smaller
pointed teeth, which are arranged in several rows.
This hunting method I could observe a few
times of my specimen, and with turning out the aquarium light
it hunted a few two or three centimetres long young Archocentrus
nigrofasciatus which had run for shelter under roots and
A rare sight: C. fowleri
completely outside of its hiding place (© W. Ros).
With the growing of these animals and primarily
at their keeping in too small aquaria, a little caution is demanded.
Because then their aggressiveness can maybe increase. Possible
aggression can even be aimed at the tank facilities like big stones
or wood but also technical equipment. With the keeping of
C. fowleri one therefore places heater, pump etc. best protected
behind an adequately strong glass case or wholly outside the aquarium.
This unpredictable behaviour is probably generally typical with
the genus Cephalosilurus, however with C. fowleri
fortunately it is much more weakly expressed.
Of course all species of the genus Cephalosilurus like
taking living fish, and C. fowleri particularly, is said
to eat only these in the aquarium at first. Apparently it can
however get used to substitute food just as quickly as C.
apurensis and C. nigricaudus do . So my specimen
has already, after a few days, willingly started to eat big earthworms
and thawed smelts, it then however accepted prawns, mussels and
fish fillets too. It is particularly greedy when receiving trout
all Cephalosilurus species C. fowleri also moves
little and therefore does not burn up much energy. Its big stomach
is able to digest large portions however this should happen over
several days like in nature. It is best that the keeper accustoms
it to a firm feeding rhythm and gives only food every three to
four days. This procedure, which is recommended for individual
keeping, however can get problematic with other fish socialized
specimens. Particularly in the summer months, if the temperature
in the aquarium rises over the usual 25 ° Celsius, one must
take into consideration the increased metabolism of the animals
by an increase of food. otherwise it can happen that they try
to overpower equal long co-inhabitants due to their increased
appetite. In principle however, this danger with C. fowleri
seems to be given far less than C. apurensis and C.
nigricaudus who are much more greedy.
C. fowleri with its first
prey, a thick nightcrawler (© W. Ros).
It is easily recognizable when C. fowleri
is hungry, because then its accommodation does not have the function
as a rest room any more but now serves as a starting point for
surprise attacks. The animal gets noticeably more restless and
altogether more attentive, it is then ready for a sudden attack.
Relations to the keeper:
For the predator catfish enthusiast this species will be something
special, especially if he has raised his C. fowleri specimen
from an early age. Interestingly this species uses its shelter
also as an observation post with respect to the keeper, so my
specimen immediately registers it if I enter the room in which
the tank is, because then it then juts its head out of its hiding
place and approaches me bit by bit towards the front of the tank.
Primarily bigger animals can be seen even if lights are switched
on and can take the food out of the hand. Until then it is a long
journey though, because C. fowleri remains rather reserved
as opposed to the other Cephalosilurus species. It is
good that they are different though as I do not run the risk of
being bitten suddenly when giving “tender loving care”.
Here the hungry predator has already become aware of me, and
thereupon partly leaves its dwelling place (© W. Ros).
C. fowleri snapping
at a given piece of fish fillet (© W. Ros).
Growth and final size:
The growth of C. fowleri is comparatively slow compared
with C. apurensis for example. When purchased as a young
animal of 10 to 15 centimetres C. apurensis is able to
take a great leap, if it is in a sufficient place and with good
feeding, and within only two years it can grow to 30 to 40 centimetres.
For C. fowleri in that same time period, 20 centimetres
is more realistic.
Its slower growth suggests a smaller final
size than C. apurensis which obliges the keeper with
the care of this species in the aquarium. The maximum length given
at Fishbase for a C. fowleri male of 40.5 centimetres
should be approximately correct . ( Fishbase
website, status of May 4th, 2008). If one compares the final
lengths having been noted for the individual Cephalosilurus
species then the impression is given, though, as if C. fowleri
is the largest of the genus. So for male specimens of C. apurensis
a final length of barely 29 centimetres is given (Fishbase
website, status of May 4th, 2008). Actually this species might
get the biggest with 60 to 75 centimetres. On various occasions
in predatory fish forums specimens are showed of supposedly, C.
fowleri, but on on closer examination turn out to be C.
apurensis. Also the final size of over 70 centimetres ascribed
to C. fowleri in some Japanese books could be explained
C. fowleri is said to attack and eat up even bigger fish.
Though the maxim applies to all Cephalosilurus species
that the keeper should decide, for single keeping in principle,
if he wants to play completely safe to lose no co-inhabitants.
On the other hand C. apurensis and C. nigricaudus
in my experience are willing and able to swallow chunks of food
much larger than their genus comrade. With them even in their
youth all co-inhabitants who are not bigger or not quick enough
permanently live in the danger of being eaten. With
C. fowleri if socialized you should be all right with
high backed co-inhabitants, especially if they are also robust
enough like most cichlids, and moreover the keeper follows the
described feeding rhythm, because otherwise this catfish, which
is living predatorily by nature will try to attack its flatmates
in the night. This danger is particularly high if you did not
think to give a weak night illumination, which ensures that other
fish can make way for it on time on its occasional nightly wanderings.
This species can safely be socialized with bigger cichlids (©
With this aggressiveness it is important to distinguish strictly
between the intra-species aggression and the aggression towards
other fish species. With intra-species aggression C. fowleri
behaves extremely aggressively and territorially. At the latest
at night, even in a big tank, the strongest animal will have pressed
its smaller comrade after a short time so that its death can only
be prevented by moving to another tank.
The same is valid if one is trying to socialize
different Cephalosilurus species. After a short skirmish
C. fowleri drove my C. apurensis back, which
I had added as a trial, and which is not only a little bigger
but seems also fundamentally stronger due to its bigger body mass.
C. nigricaudus seems to surpass
C. fowleri in aggressiveness, though.
C. fowleri in lurking
position – big specimens tend to dominant behaviour, which
however is weaker than with C. apurensis and C. nigricaudus
(© W. Ros).
Towards other big fish species C. fowleri
altogether acts peacefully, while C. apurensis and C.
nigricaudus know how to keep everybody at a distance who
approach their hiding places, by threatening gestures and if required,
by biting. The territorial behaviour of C. fowleri is
far less strongly pronounced. My C. fowleri fends off
smaller L-catfish only when they want to tackle it, are too near
or stay even in its cave. On the other hand this specimen also
has marked its area after some time in which it tolerates certain,
pre-dominantly staying in the upper half, co-inhabitants. Bottom
dwellers however know to keep at bay primarily at night. Obviously
it has already got accustomed to some Heros efasciatus
since they have been living together along with it, I could never
observe aggressions towards them. Of course the keeping of C.
fowleri in adequate big tanks together with Potamotrygon
species, with big Characins like the Red Pacu (Piaractus
brachypomus) and also other predator catfish like Lophiosilurus
alexandri which is also living in the Rio São Francisco,
The keeper should avoid socialization with
territory forming species though, because only a few centimetres
more in the body length can suddenly lead to a radical change
in the nature of C. fowleri. Presumably this change is
connected with the beginning of sexual maturity and a behaviour
which therefore is becoming more territorial. Primarily females
then shall offer increased self-confidence and play the rulers
over all co-habitants. For moving purposes it is helpful in such
a case if the keeper can resort to a further tank if necessary.
Differences between the sexes:
Females might get a little bigger than the males, especially when
older differences also consist in the coloring. Besides as in
the case of all Cephalosilurus species, the males can
be identified at the form of the genital papilla, which is longish
For the catfish enthusiast specialising in big predatory species,
C. fowleri, due to its conspicuous colour, form and movement
is worth keeping. Therefore who wants to put a “Ferrari”,
as this nickname one aquarist has not given quite wrongly to his
specimen, into a big tank, I can only encourage him to carry out
this step, particularly since this species does not prove to be
quite the bad lout either.
Werner, A. (2005): Neu
importiert - Cephalosilurus fowleri, Datz 58 (11): 29.
Ros, C. und W. Ros (2007):
Cephalosilurus apurensis - Ein gefräßiger Lauerräuber,
aber nicht ohne Charme, Datz 60 (5): 38-42.
Ros, W. (2008): Cephalosilurus
nigricaudus und seine Abgrenzung zu Cephalosilurus apurensis,
AF 40 (1), Nr. 199: 34-36.
article came out in July 2008 (p. 3-7) in the German
Online Aquarium-magazine (OAM) published by Sebastian Karkus.
Mention must be made also of our debt to Takafumi limura (Rayon
Vert Aqua corporation Japan
) who gave us kind permission to publish three pictures in this