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Hemibagrus wyckii   (Bleeker, 1858)


We welcome back Chris Ralph for an in depth look at another, what I would call, "beastie" from the genus, Hemibagrus, Hemibagrus wyckii, and also our third factsheet on this genus after Hemibagrus nemerus and Hemibagrus wyckioides. With no more ado I will now hand you over to Chris.

emibagrus wyckii
has evil written throughout its body. This is not a catfish for the novice fishkeeper and should not be kept within the confines of small aquaria. This particular species is often referred to as a “tank buster” due to the size that it can attain. These catfish are destined to be kept in solitary confinement due to their predatory and territorial habits.

Hemibagrus wyckii

This catfish is still referred to as Mystus wyckii in some aquatic literature, especially older reference books, and also by one or two aquatic retailers. It is sometimes confused also with another member of the family Bagridae, Hemibagrus wyckioides or the Asian Red-tailed Catfish which was formerly known as Mystus nemurus. These two catfish are totally different by virtue of the fact that one fish, Hemibagrus wyckii, is black, whilst the other, Hemibagrus wyckioides, is light grey to brown with a distinct red coloured tail. This catfish is very bold and has been known to attack the hand of the owner feeding it!



Hemibagrus wyckii  - showing the large mouth

For its tank size I would suggest a minimum size of 96” x 24” X 24” for a single specimen with very little if any décor. Heater guards should be provided in order to help prevent heaters being damaged by the fish, or if using a sump filter place the heater(s) within it, thus avoiding the need for heater guards. 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.


These catfish are referred to as Plakotkao by the fishermen in Thailand who also suggest that this catfish has mystical qualities.


The body of Hemibagrus wyckii is described as being depressed and broad, and the head is also described as being extremely depressed and broad. The dorsal fin spine is described as being well ossified and long with between 10 and 12 serrations on the posterior edge. Hemibagrus wyckii has a smooth flat skull roof with the occipital process reaching the basal bone of the dorsal fin. The pectoral fins have 10-11 soft rays and the pelvic fins have 6 soft rays. The caudal fin is forked.

The base colour of the body and head is black with a cream coloured coracoidal region. The caudal fin is dark grey in colour with a white to cream coloured edge to caudal fin rays. White coloured markings are present on the tips of the pectoral fins and dorsal fin, and are also present on the anterior edge of the adipose fin.


Hemibagrus wyckii is not compatible with any other fish especially smaller species as they will eventually feature somewhere on the menu!


There have not been any reports of successful aquarium spawnings of Hemibagrus wyckii to my knowledge, which I guess is not really surprising considering the fact that these catfish are not tolerant of one another.

Sexual differences
There are no documented sexual differences although it is generally thought that the females may be smaller and deeper bodied than the males.

Hemibagrus wyckii readily accepts a diet which includes pieces of fish, whole prawns, mussels and earthworms to name but a few. In its natural habitat this catfish is a predator capable of devouring any fish small enough to fit inside its large mouth.

Glossary of Terms

Dorsal: is defined as top or above.
Coracoid: is defined as middle or lower section of the pectoral girdle.
Caudal: is defined as the tail fin.
Depressed: is defined as being flattened from top to bottom.
Posterior: is defined as being situated behind.


Hemibagrus–Hemi meaning half and bagrus from bagre which is a South American name for a catfish, but is only used for African and Asian species.

Photo Credits

© Jean-Francois Helias @

Fishing Adventures Thailand

Factsheet 146

Mystus wicki, Hemibagrus wycki, Bagrus wyckii, Macrones wyckii, Mystus wyckii, Mystus wycki.  
Common Name:
Crystal-eyed Catfish.


Asia: freshwater rivers of Thailand, Mekong, Sumatra, Java, Cambodia, Viet Nam, Indonesia and Laos.
710mm s.l. (standard length – this is the measurement of the fish from the tip of the snout to the base of the caudal peduncle).
22 -26°C (71 -79°F)   
6.5 -7.2.
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                                                              Factsheet 146 = updated December 14, 2018 , © ScotCat 1997-2018  Go to Top