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Hassar orestis  (Steindachner, 1875)

ur first factsheet of 2018 takes us to a family of catfishes that are loved by most cat enthusiasts, namely the Doradidae and this month the "Black Top Mouse Catfish
", Hasser orestis has our focus. In days gone by this was in most literature, and can still be found today, under the synonym Hassar notospilus (Eigenmann, 1910).


Hassar orestis


Hassar orestis


H. orestis is similar looking to Nemadoras leporhinus but this species has longer leading fin rays and sports a clear dorsal with black markings at the base. The genes Hassar also differs from its close relative Opsodoras in having an elongate eye (Opsodoras round eye) and long snout (snout shorter with a more rounded profile in Opsodoras)




Hassar orestis = showing the long snout and the elongate eye


For a large species it is non aggressive and can be kept with smaller species such as small characins, dwarf cichlids, small labyrinth species and also other small catfish such as Corydoras and the smaller members of the Loracariids. Provide a soft substrate such as fine sand as they like to sift through this for edibles and a sharp substrate could cause damage to its fine feathered barbels.




Head narrow with long snout. Maxillary barbels reaching pectoral, with small barblets. Mental barbels papillose. Lateral plates small, the largest approximately 1.33 times the size of the eye. Large foramen present on occipital process.

Body light grey, underside white. Minute black spotting around base of dorsal. Conspicuous black blotch in dorsal.

Aquarium Care

This is a particularly delicate aquarium fish with low tolerence to adverse water conditions and disease. Lone individuals will not do well in an aquarium setup so a group of three or more will be more beneficial to the long term health of this species. A planted aquarium is a must as they like to hide in the roots more so than having a rock or wood setup.



Can be kept with smaller species such as small characins, dwarf cichlids, small labyrinth species and also other small catfish such as Corydoras and the smaller members of the Loracariids.



No reports.

Sexual Differences

Males possess an elongated first dorsal ray. Females have more rounded pectoral fins than males.



Tablet foods, small live and frozen foods such as worms and Daphnia.

Glossary of Terms

Maxillary barbels: Pertaining to the upper jaw. (maxillary barbels)
Mental barbels: Pertaining to the chin, on the lower jaw. (mental barbels)
A small fleshy projection, plural papillae.
Lateral: A sensory line, along the sides of the body.
Foramen: magnum (Latin: great hole) is a large oval opening (foramen) in the occipital bone of the skull in humans and various other animals. It is one of the several oval or circular openings (foramina) in the base of the skull.
process: A median bone on the upper surface of the back of the head; pertaining to the occiput.
Dorsal: The primary rayed fin(s) on top of the body.


Hassar: From the Aruac name of the fish.
orestis: A mountaineer.


Baensch, H.A. and R. Riehl 1985 Aquarien atlas. Band 2. Mergus, Verlag für Natur- und Heimtierkunde GmbH, Melle, Germany. 1216 p
Catfish Association of Great Britain: Information Book 6, 1980. 18p.

Photo Credits

© Daniel Blom

Factsheet 259

Oxydoras orestis, Hassar notospilus, Hemidoras notospilus
Common Name:
Black Top Mouse Catfish
South America: Amazon, Orinoco and Essequibo River basins
20.5cm. (8¼ins)
22-25°C (71-77°F)
6.0 - 7.5.
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