nigriventris David, 1936
his is one of the few catfishes in the earlier days of the hobby
that was enough to make you into a catfish 'freak' along with Synodontis
angelicus, flavitaeniatus and decorus of this
same family, the Mochokidae. These days it is the colourful Loricariids
such as the 'Zebra Plec' and the 'Golden Nuggets' that bring new
blood to the catfish fraternity.
nigriventris was first described in 1936 and caused quite
a stir when it was first exported in 1950. One of the first
articles on 'the curious fish that swam upside down' was
by Fraser-Brunner in the November 1950 edition of Aquarist &
Pondkeeper and he pointed out that this upside-down catfish
may have been new to the aquarium hobby but was not new to the ancient
Egyptians who frequently depicted them in their wall-paintings and
Now the question: 'why do they swim upside down'?. You will notice
that the body colour is reversed with the emphasis on the belly
being darker as with most other fish this area is lighter so when
looking underneath they merge into the light that comes from above
and the back is darker to presumably give them some protection from
predatory birds. The reverse is somewhat true of Synodontis nigriventris
as they feed on the surface upside down. I say somewhat true
as the back is only a few shades lighter and sometimes the difference
is not all that apparent.
A scientific study was carried out in 1976 on this peculiar upside
down scenario, why doesn't this fish get forced back over to its
'rightful position'? The swim bladder was normal and there was nothing
untoward about the balancing organ of the ear, as it resembles that
of other catfish, but what they found was that the nervous circuitry
between the brain and the balancing organ of the ear is rather special,
as it can be reset to zero once the body has tilted more than a
certain critical degree (about 22 degrees).
The picture above shows the correct way
to house this catfish in your tanks. They like to have their bellies
pressed up to a surface and bogwood and branches seem to be their
favourite foible. They also prefer to be kept in a group where
they can interact with one another. A small to medium sized tank
with plants floating and submerged and branched rootwork is the
ideal environment for this peaceful Synodontis.
The genus Synodontis sports three pairs of barbels 1pair:
maxillary, 1 pair: outer mandibular and one pair of inner mandibular
barbels that are branched (filaments). There are only three species
that have filaments on their maxillary barbels as well as the
mandibular, and they are, S.clarias,
There is another variety named S.nigriventris
"zebra". It may be an undescribed species or it may
be just a colour variety of the normal nigriventris,
only time will tell on this issue. The normal nigriventris
comes from all over the Congo drainage and the "zebra"
variety from the region around the town of Kutu, Bandundu and
Lac Leopold 11 in the Dem. Republic of the Congo.
Dorsal: 1/7, Anal: 4/4-9 Characteristic of
this species is the smooth anterior face of the dorsal spine, the
narrow separation of the eyes and the large size of the eyes.
Pale grey to cream-coloured with dark
brown to black blotches which may run together to form irregular
broad transverse bars. Belly uniformly black (nigriventris).
The fins are often darkly spotted on a colourless ground.
A peaceful occupant of your community tank.
Should not be housed with aggressive species such as large Cichlids.
It is one of the few Synodontis to
be bred in captivity although the few successful attempts have been
sketchy and they have been mostly by accident. There have been reports
that they lay their eggs in a depression in the gravel and also
another report when they laid them in a PVC pipe and also flowerpots.
The young seemingly revert to the upside down pose when about 10
A good regime for a breeding setup would be to provide pipework
and a few clay flowerpots with a gravel substrate and the usual
plants and wood to make them feel comfortable thus giving them choices
for a hopeful spawning. The females are more noticeably plumper
than the males and a bit more lighter in colour.
In their native habitats they feed on insect
larvae at the water surface and also scrape algae of the underside
of leaves. A good diet of a good quality flake food, tablet food,
frozen bloodworm and livefood such as daphnia should suffice.
Dr. Michael Benjamin; Aquarist
& Pondkeeper, Feb.1986.
Syn = together; odontis = teeth.(fused
nigriventris: Black belly.
J comp. Physiol; vol 110, p 323-331 (1976)