nijsseni is one of
possibly four other orange blotched species which are
found in the upper Rio Negro drainage in Brazil. The
other four which are sympatric with C. nijsseni
All these species are variable in their colour patterns.
The main crieria
that seperates C.nissseni from the other species
is the body shape, very much C.elegans like.
If you looked and discounted the colour pattern you
would think that you were looking at C. elegans
or one of the same body shape i.e. C.
nanus or C.
napoensis. Of course
C. elegans is found many miles away in the
south of the country in the Rio Amazonas at Tefé.
Like all the orange-blotched
Corydoras from the upper Rio Negro drainage,
Corydoras nijsseni is very variable in the
black parts of the colour pattern. There are forms with
broad and forms with very narrow stripes, depending
on the locality. The other orange spotted species which
are syntopic with Corydoras nijsseni mostly
show the same variation. The form with a very broad
band (only in males), has been erroneously given the
C-number C111 (Fuller; Evers, 2005).
The orange head
patterns and the black eye mask of all these 5 species
must have an advantage when shoaling together as the
chance of predation would diminish with such a large
group turning one way and then another in a great swarm.
I think a good experiment
would be to introduce this species in a largish aquarium
maybe 3ft long by 18ins wide and 12ins high with a group
of C.axelrodi and C.imitator and to
be able to watch the interaction between these three
similar looking Corydoras species.
I have kept and
successfully bred this species in the early nineties
and like Corydoras elegans it likes to swim
in the middle layers of the aquarium and like elegans
it also lays very small eggs on the tank sides and on
the java moss.
I found this quite
a timid species and would bolt for cover if disturbed
by myself or anyone entering the fishhouse.
The holotype of
C. nijsseni was deposited in the Rijksmuseum,
Corydoras nijsseni is part of the so called "Elegans
Group" which would place it in Lineage 5. A revision
in the future could involve the resurrection of the
genus name Gastrodermus (Cope, 1878), with
the designated type species: C. elegans.
Main whitewater tributaries of the Rio Negro and upriver
from Sao Gabriel da Cachoeira.
Male: 4.5cm (1¾ins)
Female: 5.0cm (2ins)
Dorsal: 1,7; Dorso-lateral
scutes: 21; Ventro-lateral scutes: 19. The pectoral
spines are thorned on the posterier edge with the
anterior edge being barely serrated.
Dark head, almost to the posterior
edge of the eye. Orange band behind the eye but anterior
to the dorsal fin at which point, a dark, typical
'adolfoi/imitator' narrow black line arises
and extends from the dorsal fin laterally to the caudal
fin. All the fins are clear of pigment.
Care & Compatibility
Like most species of Corydoras
they are peaceful and and would do fine in a community
aquarium with smaller compatriots such as small Tetras
The males tend to be slightly
smaller and more slender than the females and have a
more ornate pattern whereas the females look plainer.
The ventral fins of the males tend to be more pointed
than those of the females. Sexing of these catfish is
easier when being viewed from above.
Lays their eggs in Corydoras
fashion on the glass sides and plants especially in
the fronds of Java Moss plants. For more information
on the breeding of the many varieties of Corydoras
you can find many articles in the Breeding
As with all Corydoras
they accept a mixed and varied diet. Good quality
flake foods, granular and tablet foods, cultured whiteworm,
grindal worm and frozen foods such as bloodworm.
scutes: The bony covering extending from
the top to the side.
Sympatric: Referring to two or more species
living in the same or overlapping geographical area. Ventro-lateral scutes: The bony covering
extending from below and to the side.
Corydoras:Cory = helmeted; doras =
leathery skin, (helmeted Doras) cuirass. nijsseni: Named in honour
of Dr. Han Nijssen of the University of Amsterdam.
Markos & Taylor, Martin. (2011). Evolution,
ecology and taxonomy of the Corydoradinae revisited.
Ian A. M. Fuller & Hans-Georg Evers
2011, Identifying Corydoradinae Catfish: Aspidoras-Brochis-Corydoras-Scleromystax-C-numbers
& CW-numbers 141p. Ian Fuller Enterprises. Sands, David; Two New Species of
Corydoras: Aquarist and Pondkeeper August 1990.