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Oxydoras niger  (Valenciennes, 1821)   

In this, the last month of 2005, we welcome back Chris Ralph a regular contributor to ScotCat and who also writes for the largest circular fishkeeping magazine in the U.K., "Practical Fishkeeping". He is also an author in his own right with a few books now on the hobby. Without further ado Chris will explain the doe's and don'ts of keeping one of my own favourite big cats, Oxydoras niger, the "Mother of Snails Catfish".

he Mother of Snails Catfish is not a very commonly seen doradid, although if you have kept one then it is one that you will not forget in a hurry due to the size that they can grow to. These catfish are usually offered for sale as juvenile specimens at around 4” in length. To the unsuspecting aquarist they have probably taken on more than they bargained for! This said if you are a genuine enthusiast you would already know a bit about these fish and their requirements prior to their purchase. The colour of these fish is basically dark brown to black, hence their other common name name "Black Doradid".

Oxydoras niger

If you own one of these catfish you will know that feeding time can be a rather wet experience, even with tight fitting cover glasses, or in my case an open topped pond! I have lost count of the number of soakings that I have had over the years! I purchased my first Mother of Snails Catfish about twenty years or so ago. The first one that I owned was around 10” long SL (25cm) and very rapidly outgrew a 72” x 18”x 18” aquarium. I eventually purchased a larger aquarium 72” x 24” x 36” and went on to keep this fish for a number of years. When the fish died from a bacterial infection it was almost 28” in length, and would have required an even larger aquarium before too long. This was really the main reason behind the construction of the Tropical Pond, although at present I am not keeping any large catfish. The Mother of Snails Catfish belongs to the Family Doradidae, all of which originate from various locations throughout South America.

Oxydoras niger  = showing barbels


Sometimes literature refers to the doradids as “Talking Catfish” due to the fact that they can be heard to make audible noises, almost as if they are speaking to one another. There have been no records of these catfish having been successfully bred under aquarium conditions yet, which is probably just as well!


One of the main characteristics of the doradids is the presence of thorn like projections along the side of the body, which are known as scutes. These scutes are very sharp, so care should be taken when moving these fish.

Occasionally amongst imports of Oxydoras niger there are the odd slightly different specimens which tend to have black coloured fins and a grey coloured body, which are Pseudodoras holdeni

A real “Tank buster” if ever there was one. Quite a character obviously suited to large accommodation especially if keeping a number of fish together. Peaceful towards other fish and members of its own kind. Other doradids such as Agamyxis pectinifrons (Spotted Dora), Platydoras costatus (Striped Dora), Oscars and any other fish of a compatible size. Large pieces of bogwood and clean plastic drainpipe of suitable diameter for them to hide under. Ideally heater guards should be provided in order for the fish not to burn themselves.

There are no known external sexual differences. There are however some thoughts and suggestions that there may be some differences in the shape of the bony plates which extend from the head to the edge of the pectoral fins. It has been suggested that the male has a more pointed plate, whilst the female has a more rounded plate. There is no scientific evidence that is available to support this observation.

As yet unknown.

Readily accepts all manner of prepared foods. Stinking Sinking Catfish Pellets are high on the list, alongside floating pellets and sticks, as well as frozen bloodworm, chopped mussel and earthworms.

Oxydoras: Oxys = sharp; doras = cuirass ( helmeted)
niger : Black body colour

Previously published in the September 2005 edition of Practical Fishkeeping magazine.

Photo Credits
© Allan James ScotCat  courtesy of Pier Aquatics 


Factsheet 114

Doras niger, Doras humboldti, Pseudodoras niger, Corydoras edentatus, Rhinodoras niger, Rhinodoras prionomus, Rhinodoras teffeanus.  
Common Name:
Mother of Snails Catfish, Ripsaw Catfish & Black Doradid
Amazon region, Peru, Brazil, Rio Purus, Rio Sao Francisco.
In excess of 90cm (36ins)
21-24°C (70-75°F)     
pH 6.0 to 7.8 with up to 25 dGH hardness
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                                                                                                     Factsheet 114= updated December 14, 2018 , © ScotCat 1997-2018 Go to Top