Article © Chris Ralph, uploaded August 05, 2009.

Chris Ralph and I were fortunate enough to both visit the Peruvian Amazon for our first times on the same trip - we encountered many interesting catfishes and Chris introduces one of them this month.

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. This catfish belongs to the sub-family Cetopsinae.

Cetopsis 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.

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 which exceeded this length and were 300mm+!

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.

I would suggest a minimum size of 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.

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.

Copyright information for the images used in this article can be found on the species' full Cat-eLog page.

Cat-eLog Data Sheet
Scientific Name	Cetopsis coecutiens  (Lichtenstein, 1819)
Common Names	Baby Whale Catfish Blå Vampyrmalle (Denmark), Blue Shark Catfish, Blue Torpedo Catfish, Blue Whale Catfish, Whale Catfish
Type Locality	Rivers of Equatorial Brazil.
Synonym(s)	Silurus coecutiens
Pronunciation	see TOP siss - koe cutey enz
Etymology	Cetopsis: From the Greek cetos, meaning whale, and -opsis, meaning likeness; in reference to the whale-like appearance.
Articles
Species Information
Size	265mm or 10.4" SL. Find near, nearer or same sized spp.
Identification	An uncommon import but commonly encountered in its natural habitat - a couple of hours hook and line night fishing in Peru yielded a dozen or so of these fish. Several other members of the family are imported rarely.
Sexing	Males are more slender than females and their dorsal fin tapers to a more elegant point in mature specimens.
Habitat Information
Distribution	South America: Amazon, Tocantins, and Orinoco River basins. Amazon (click on these areas to find other species found there) Amazon, Lower Amazon, Tocantins (click on these areas to find other species found there) Orinoco (click on these areas to find other species found there) Orinoco, Middle Orinoco, Apure (click on these areas to find other species found there) Log in to view data on a map.
IUCN Red List Category	Least Concern, range map and more is available on the IUCN species page. Last assessed 2020.
pH	6.0 - 7.4
Temperature	22.0-26.0°C or 71.6-78.8°F (Show species within this range)
Other Parameters	An open water fish that requires strong current and oxygenation. It is a testament to the fishes adaptability that it survives in conditions less than this ideal. Water quality and general husbandry is important, and it is recommended that a minimum of 25% water is changed on a weekly to fortnightly basis.
Husbandry Information
Feeding	Will accept frozen foods and readily adapts to all good sized live foods. Chopped mussels and live earthworms are favourites. Should not be weaned onto feeder fish but attempts to wean onto tablet food (especially shrimp based tablets) should be made from a young age. Be careful not to overfeed as this fish is an opportunistic feeder and will gorge itself given the chance. User data.
Furniture	A sparse, dimly lit tank is required. Provide only minimal cover for the fish to hide in during the day. The provision of a dim actinic light will allow you to observe the fish on its nocturnal prowling where it is an impressive midwater fish and needs room to roam. Substrate is important as although it is a midwater fish, it comes to rest on the bottom frequently. Use aquarium sand or rounded gravel.
Compatibility	Not a fish to be trusted with others. Its natural adult behaviour is to bite lumps out of larger deep river channel fish such as the scaleless Pimelodids. Younger fish in the aquarium do not seem so dangerous, perhaps because they are young or well fed. It will however always eat smaller fish and is an accomplished hunter.
Suggested Tankmates	It is believed these are a shoaling fish, but no data is available on keeping them as such in aquaria. Perhaps armoured catfish are the best bet, but ensure all fishes are well fed.
Breeding	Unreported and good luck trying to raise a brood of these things!
Breeding Reports	There is no breeding report.
Further Information
Reference	Zoologisches Magazin (Wiedemann) 1819, v. 1 (pt 3), pp 61.
Registered Keepers	There are 10 registered keepers, view all "my cats" data.
Wishlists	Love this species? Click the heart to add it to your wish list. There are 3 wishes to keep this species, see who wants what.
Spotters	Spotted this species somewhere? Click the binoculars! There are 9 records of this fish being seen, view them all.
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	Look up C. coecutiens on Encyclopedia of Life
	Look up C. coecutiens on Global Biodiversity Information Facility
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Last Update	2020 Sep 16 01:39 (species record created: 2009 Aug 05 12:52)

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