Corydoras nijsseni
Sands, 1989 |
orydoras 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 are: C.adolfoi,
C.duplicareus, C.imitator and C.serratus.
All these species are variable in their colour patterns.
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Corydoras
nijsseni = female
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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).
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Corydoras nijsseni = male
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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,
Leiden, Germany.
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.
Like most species of Corydoras they
are peaceful and and would do fine in a community aquarium with
smaller compatriots such as small Tetras and Rasboras.
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
Articles section.
| Sexual
differences |
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.
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| Feeding |
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.
| Glossary
of Terms |
Sympatric:
Referring to two or more species living in the same or overlapping
geographical area.
Dorso-lateral scutes: The bony covering extending
from the top to the side.
Ventro-lateral scutes: The bony covering
extending from below and to the side.
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| Etymology |
Cory
= helmet, Doras = skin.
nijsseni = Named in honour of Dr.
Han Nijssen of the University of Amsterdam.
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| References |
Fuller, A.M. &
Evers, Hans-Georg: Identifying
Corydoradinae Catfish P.182-183
Sands, David; Two New Species of Corydoras:
Aquarist and Pondkeeper August 1990.
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| Photo
Credits |
Top: Allan
James @ 
Bottom: Ian Fuller @  |
Brazil;
Main whitewater tributaries of the Rio Negro and upriver from
Sao Gabriel da Cachoeira
