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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