Cetopsis coecutiens (Lichtenstein,
1819) |
This month we welcome back our resident catfish
contributor, Chris Ralph, writer and catfish expert in the U.K.
fishkeeping magazines. This factsheet is close to my heart, so to
speak, as I joined Chris and other catfish buffs on a memorable
trip to Peru and the Amazon in 2000 and this catfish was one of
the first that I had seen when we caught them from the boat on rod
and line. They are not a pretty sight so I will let Chris explain
and educate us on the "Whale Cat", Cetopsis coecutiens
etopsis coecutiens
is one of the largest of the so called species of “Candiru”
and is viewed with some trepidation amongst a number of catfish
enthusiasts. Unfortunately or fortunately depending upon your personal
views, Cetopsis coecutiens is not commonly available to
the hobbyist. When this unusual catfish is available, expect to
pay £20-£25 per fish. In their natural habitat these
catfish are very much opportunist parasites feeding upon other fish,
literally biting chunks of flesh from the body of their unfortunate
victim. These catfish are often found inside the body cavities of
larger fish such as the Red tail catfish – Phractocephalus
hemioliopterus and Tiger shovelnose – Pseudoplatystoma
fasciatum! These catfish are found in relatively large numbers
in their natural habitats.
Cetopsis coecutiens
belongs to the family Cetopsidae or Whale Catfishes from South America;
namely the Amazon basin, Peru, Bolivia, Colombia, Ecuador, Venezuela
and Brazil - Tocantins and Orinoco River basins.
Although it is documented that this catfish reaches a size of 265mm,
whilst collecting catfish in Peru in July 2000 a number of specimens
were caught on rod and line ( see image below) which exceeded this
length and were 300mm+!
Cetopsis coecutiens
prefer to be kept in water which has a pH in the range of 6.0-7.4.
This catfish is ideally suited to temperatures in the range of
22-28ºC. Cetopsis coecutiens is naturally an open
water swimming fish and as such requires well aerated water with
a strong current in order to keep it in optimum conditions.
I would suggest a minimum size of Aquaria to be 72” x 24”
X 24” if you are going to keep these catfish until they
attain adult size. There is no real preference of substrate when
keeping these catfish however; I would suggest good quality aquarium
sand such as BD Aquarium Sand, or very smooth rounded gravel.
The aquarium should provide minimal shelter in the form of rocks
or bogwood due to the fact that this catfish is constantly on
the go, swimming in the midwater regions of the water body. As
with all other species of fish, water quality and general husbandry
is very important, and I would recommend that a minimum of 25%
water is changed on a weekly basis due to the fact that these
catfish are constantly looking for food and the diet is fish or
meat based. Lighting should be dim, due to the poor eyesight of
these catfish and the fact that they are found at relatively deep
water levels in their natural habitat.
Did you know? – This particular catfish was recently featured
in the BBC series Amazon Abyss, and was seen still feeding upon
the carcass of a catfish even after it was taken out of the water!
The body shape of Cetopsis coecutiens
is described as being cylindrical, torpedo or cigar shaped. The
body is also best described as being naked or devoid of scales.
The pectoral fin spines are not serrated. The eyes are small in
comparison to the rest of the body and are often described as being
“piggy”. The mouth is relatively large in comparison
to the rest of the body with the mandible being under slung, with
the maxilla protruding, almost giving the appearance that the fish
is smiling
The base colour of the dorsolateral region
of the body and head is blue, whilst the ventrolateral region is
predominantly white in colour interspersed with some patches of
blue towards the head. The dorsal and caudal fins have some blue
colouration whilst the remaining fins are white in colour.
Wherever possible I would recommend that the
aquarist keep these catfish in a species only aquarium in small
groups, but as the absolute minimum I would suggest two to three
specimens assuming that they are available in these numbers. In
their natural habitat Cetopsis coecutiens would be found
in very large shoals. This catfish is not a species to be trusted
in with other species due to its ability to bite lumps out of other
large fish, and would soon devour any small fish within the confines
of its environment. With this information in mind I would not recommend
that you keep any other fish with these catfish.
As far as I am aware there are no documented
records of Cetopsis coecutiens having been spawned in aquaria
to date (but then who would want to?).
| Sexual
differences |
The males tend to be more
slender than the females. The dorsal fin of the male tends
to be more pointed in mature specimens.
|
| Feeding |
As with all the other catfish that I have
had the pleasure to keep over the years, Cetopsis coecutiens
readily accepts a mixed but meaty varied diet. I found that these
catfish relished meaty foods such as whole mussel, cockles, prawns
and earthworms and after a while they even accepted the occasional
sinking catfish pellet! A word of caution though, these catfish
will easily gorge themselves if given too much food, so you need
to ensure that these catfish are not overfed.
| Etymology |
Cetopsis:
from the Greek cetos which means whale, and cosis which means
like, hence the reference to this catfish being whale-like
in appearance.
|
| Glossary |
Ventrolateral:
is defined as extending from below and to the side.
Dorsolateral: is defined as extending from
the top to the side.
Maxilla: is defined as the bone of the upper
jaw.
Mandible: is defined as the lower jaw.
|
Chris Ralph |
|
|
| Synonyms:
|
| Silurus coecutiens,
Silurus caecutiens |
| Common
Name: |
| Blue Whale Catfish, Whale
Catfish, Baby Whale Catfish, Blue Shark Catfish, Blue Torpedo
Catfish or Candiru |
| Family: |
| Cetopsidae |
| Subfamily: |
| Cetopsinae |
| Distribution: |
| South America;
namely the Amazon basin, Peru, Bolivia, Colombia, Ecuador, Venezuela
and Brazil - Tocantins and Orinoco River basins. |
| Size: |
| 265mm s.l. (10½ins)
(standard length – this is the measurement of the fish
from the tip of the snout to the base of the caudal peduncle) |
| Temp: |
| 22 -28°C (71 -83°F)
|
| pH.: |
| 6.0 -7.4. |
| Donation: |
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