TankBud

Blue whale catfish

Cetopsis coecutiens

FreshwaterFish

Blue whale catfish (Cetopsis coecutiens)
Jansen Zuanon & Efrem J. G. Ferreira · CC BY 4.0

Care at a glance

Temperature
72–79°F
22–26°C
pH
6.0–7.5
Adult size
10.6 in
27 cm
Minimum tank
70 gal
265 L
Temperament
Aggressive
Social behavior
Solitary
Tankmates
Species tank only
Swim level
Bottom
Diet
Carnivore
Difficulty
Difficult
Breeding
No record
Rarity
Very rare
Family
Cetopsidae
Origin
South America

Overview

The blue whale catfish is a fast, aggressive predator that is best kept entirely on its own. It is a fish for experienced keepers only.

Did you know

The blue whale catfish is one of the largest members of the candiru group. It feeds much like its smaller relatives, ripping mouth-sized pieces of flesh from fish far bigger than itself rather than swallowing prey whole.

Caring for the blue whale catfish

Keep the blue whale catfish as a single specimen in a tank of at least 70 gal (265 L). It is powerful and restless, so the tank needs to be secure, with open swimming space and firmly weighted caves. A dim setup with a smooth sand bed and scattered heavy wood mimics its muscular river home. Bright lighting is unnecessary, since it has tiny eyes and hunts largely by smell and touch.

It favors warm, soft water at 72 to 79°F (22 to 26°C) and a pH of 6.0 to 7.5. Give it brisk current, high oxygen levels and strong filtration.

Feed meaty foods such as chunks of white fish, prawn, mussel and earthworms. It will swallow smaller companions and bite chunks out of bigger ones, so it is not a community fish under any circumstances. Its breeding habits are unrecorded in aquariums.

Good to know

The blue whale catfish belongs to Cetopsidae, the whale catfishes, and some wild fish grow a little larger than the usual adult size. It has a smooth, scaleless, almost cetacean body and a wide mouth built for gouging. Adults are notorious for sometimes entering the body cavity of dead or hooked animals to feed.

In the wild

The blue whale catfish ranges widely through the Amazon basin of South America. It lives in the open channels of large, fast-flowing rivers rather than quiet margins.

Common questions

What size tank does a blue whale catfish need?

A blue whale catfish needs at least 70 gal (265 L). It spends most of its time in the bottom.

What temperature and pH does a blue whale catfish need?

A blue whale catfish is comfortable at 72–79°F (22–26°C) with a pH of 6.0–7.5.

What does a blue whale catfish eat?

A blue whale catfish eats meaty foods, such as chunks of white fish, prawn, mussel and earthworms.

How big does a blue whale catfish get?

An adult blue whale catfish reaches about 10.6 in (27 cm).

Related species