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
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
and Tiger shovelnose – Pseudoplatystoma
These catfish are found in relatively large numbers
in their natural habitats.
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+!
coecutiens - caught on rod and line
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!
Whale Catfish, Whale Catfish, Baby Whale Catfish,
Blue Shark Catfish, Blue Torpedo Catfish or Candiru
Namely the Amazon basin, Peru, Bolivia, Colombia,
Ecuador, Venezuela and Brazil - Tocantins and Orinoco
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)
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
Care & Compatibility
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?).
The males tend
to be more slender than the females. The dorsal fin
of the male tends to be more pointed in mature specimens.
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.
Defined as extending from the top to the side. Mandible: Defined as the lower jaw.
Maxilla: Defined as the bone of the upper
Ventrolateral: Defined as extending from
below and to the side.
Cetopsis: from the Greek cetos which means whale,
and cosis which means like, hence the reference to
this catfish being whale-like in appearance.